I'll tell you why: Merc Pyro is still INFERIOR to Powertech Pyro.
Merc pyrotech is absolutely 100% is inferior.
I duel with a Powertech who is just as geared as me. (I've done several of these tests with competent people as a true indicator, not posting ridiculous screenshots that give the illusion of competence).
The powertech may have a range nerf on two abilities, but because of Dart being off the same cooldown as TD, it all evened out. Most PT's aren't even using the IM near as much and benefiting from the reduced heat issues.
So the 'nerf' is really only applicable to TD. BUT the buff to -Dart- made up for it.
Even if you understand what I'm saying here, you might still be asking why I would believe Powertech is better at Pyro. Here's why:
1) as shown above, the nerf really isn't much of a nerf thanks to other changes.
2) Grapple is on a pretty darn low cooldown and it is GREAT at isolating healers from their guards, and COMPLETELY eliminates any 'range nerf'.
3) Pyrotech resets Rail Shot on 2 INSTANT abilities, not channeled/cast time abilities: Rocket Punch and Flame burst. So while you're standing there trying to get off a cruddy "Powershot" so you can proc a Rail shot, you're getting interupted or grappled by the PT and he's flame bursting you down, and getting his free rail shot.
4) The powertech pyrotech can also trump you in the stun game. I can't remember the last time I faced a competent melee type that let me Concussion them, but that still leaves Mercs with Electro Dart. Well Pt's have Electro Dart AND Carbonize. What about our AoE knockback? It's an interrupt (on a non-interuptable opponent) at best. It doesn't knock back far enough in Pyro to be of any consequence in most maps.
I can and have pulled HUGE numbers in non-ranked WZ's. I even have one ranked screenshot of over 500K against a total group of ungeared players trying to get comms. But when it comes down to it, the Powertech does Pyro better. Even if you want to convince your self of some fantasy scenario where you love using channeled abilities in PVP, you cannot argue the base mechanics of two classes and how they reset rail shot.
I wasn't comparing Merc Pyro vs. PT Pyro situations. Given a 1v1 duel, the Merc (any spec) would lose to any class in the game currently. I am not trying to make people believe I could somehow change that with playstyle. I cry for mercs, I really do, and I hope they get fixed asap.
But I will say, that it's not impossible for the Merc to win. You can kite the PT if you start at 10-30m range (you both can only snare with rapids while moving and at 30m range, so you should be able to move away as fast as the PT is closing on you, just don't backpedal). If the PT grapples you, you should immediately jet him + cleanse any dots you might have (CGC snare), which will again put you into + 10m, which means you should win. This is due to the range nerf on Electro Dart, which again, benefits the Merc a lot, being more ranged ability.
But, you do have to think about 8v8.
In 8v8 situation, PT pulling you usually means you are a called target, and in a lot more trouble than you would think. Then it's up to your team to save you, but you kinda have to think, that it's better you got pulled, than say, your healer. You being pulled means many things. Their team having 1 less pull, and your team most likely able to save you via heals + guard + taunts. And don't forget, that you can actually use LOS yourself as a Pyro Merc, so that dodgy grapple might just pull you towards a wall/box you are behind, and make the PT very sad.
As for the 30m mezz. It does not compare to the Flashbang, which is instant AoE, and I would definately not use it against melee classes. As a Pyro the problem is not that much that you can't, but the fact that you can't after starting to damage, because of the DoTs and them breaking the mezz. You could make it an instant cast and use it otherwise. If you can't handle the melee (Most maps, some situations in Voidstar, and Huttball you might be able, but otherwise it is unlikely) you need to call for help. I'd say the most beneficial use of the mezz, is ranged casters, DPS/healers that you can shut down for a long time, after they have used their CC breaker. Use it on a non focused target, or call it out in ts if you are in one, since you don't want it to get broken.
As a Merc, you're ofc specced into 1.5 sec PS and 75% pushback reduction on your casts, so interrupts are the only problem at that point. That means the Merc can do more front load dmg, since PS procs the Rail at the end of the cast. Also, don't forget that Unload procs at the start, so it doesn't matter if you get interrupted, you can use Unload as an 'instant' Rail proc. Like so:
Merc: IM + Rail + Unload (proc, following a full 3 sec cast) + Rail + PS (proc) + Rail. = 3 Rail in 10.5 seconds. This can be done at 30m.
PT: IM + Rail + FB + Rail + filler + filler + RP + Rail. = 3 Rail in 12 seconds. This requires 10m in 1.4.
Ofc PS can still be troublesome, because of LOS and interrupts, I am not arguing with that.
But let's now compare the abilities that are supposed to 'mirror' each other. The Power Shot (Merc), and the Flame Burst (PT)
Tech (= Cannot be dodged/shielded = Guaranteed hit)
Elemental Damage (= Armor does not apply)
100% proc chance on CGC (= A heavy DoT + Snare)
2.0 sec cast time, 1.5 with talent.
Ranged (= Can be dodged/shielded = Not a guaranteed hit)
White Damage (=Armor applies)
No 100% proc chance on CGC
Now, somehow it seems to me, that BW has this idea that close range DMG dealers need more dmg/burst compared to ranged, since they cannot be on their target/switch targets as easily. This is totally retarded, as a melee gets a gap closer, and they get the tools to stick to their target(s). While they cannot always switch targets (So, they cannot perhaps always deal DMG), this is the same to Ranged DPS as well. Ranged DPS have casted abilities = They can, and will get LOSd = They cannot deal damage 24/7 either.
So, I guess the reasoning behind FB being a heavyweight champ, and PS being a featherweight loser, is that somehow 30m is supposed to be awesome. BW, please read this carefully: A class needs to be viable in it's EFFECTIVE range. Merc is 30, PT is 10. FB and PS should be equally powerful abilities, regardless of the range difference. Merc being not effective at 30, and PT being effective at 10, is just retarded.
I mean, even if they made PS an INSTANT cast, Mercs would not top the charts. There's still GCD 1.5s, so nothing would really change, other than not getting shut down so easily. It would be fine. They would be able to get their procs on rail, but that lack of a guaranteed CGC and snare will still leave them open for melee/close range classes. And, if they would keep it 2.0/1.5 casted ability, giving it the same 100% proc on CGC would not make them overpowered either, since the ability is still ranged, so it's still not a 100% guaranteed hit (=Not a guaranteed CGC proc either). This would still held true, even if it were an instant cast. And, even if they did both, because Tech&Elemental vs. Ranged&WhiteDMG, they would still not be equal. Read that again:
Making PS and instant cast, and giving it a 100% CGC proc chance would still not bring it to equal grounds with FB.
So just think how ****ed up the situation is, when PS is what it is today.
I'm currently lvl 41 with my Merc, so I'm still learning, and will further update you on when I have her on full WH lvl50, which shouldn't take too long, as my PT alrdy has all the armor pieces rdy with full WH min/maxed mods.
While I'm going to focus on the Pyro, I have some thoughts on Arsenal spec as well, and why it is totally gimped compared to the other ranged DPS classes. F.e a sniper. He's a caster. You're a caster. He can't be leaped to. You can. He can't be interrupted. You can. He can also be immune to all controlling abilities (stuns, mezzes, kbs, interrupts). He can also lower the damage on any DPS coming from ranged sources. He has best range defenses in the game, which is what armor only applies to (together with melee), so in fact, a sniper has better 'armor' than you in most cases where the sniper doesn't get a melee close to him, since he will not get hit in the first place, with ranged attacks. It is the issue of defensive cooldowns. But more of this later...