The major issues with AP, the condensed version:
Ion gas cyllinder is required for survivability and guard.
The big reasons to go AP (increased combat mobility and heat management) are tied to HEGC which is currently abysmal.
Retractable blade does lackluster damage for the focus the AP tree has on it.
Flamethrower is nigh impossible to use effectively in pvp in its current incarnation.
Pyrotech does everything AP does better except the afformentioned combat mobility and heat management. But that's somewhat rectified by degauss and shortened vent heat timer.
In many instances shieldtech gets greater mobility in the form of jet charge and if you with to take it, an extra 30% movement speed after using jet charge.
IGC is required because AP lacks survivability despite being a melee spec who lacks a gap closer and escape maneuvers. You should not be guarding if you are a AP - you are only asking for trouble. Some debuffs in the AP tree that reduce enemy damage would be well received without overpowering the spec.
Retractable Blade does low damage because outside of AP the Powertech does not do bleed damage. However, the Powertech has multiple talents increase fire damage, which helps PyroTech's burn DoTs a hell lot. PyroTech has better DoTs and, because of Rail Shot CD refresh, better burst. It's nuts. I think a simple fix would be to also increase bleed damage with all the talents that increase fire damage (Intimidation, Prototype Burn Enhancers) as well as buff Serrated Blades.
Not commenting on the rest because they just affirm my previous points (thanks for the support).
I appreciate your effort and agree with most of your points. Having another dps option would bring a lot to my PT experience.
AP already is a good DPS option, it's just not as good as it should be. You should spec AP if you enjoy it; if you are a good player you will still top PvP charts and do amazingly well in flashpoints and operations. The only problem is that if you apply that same skillset to PyroTech, you do even better.
AP needs buffs and some tweaks, but it is still viable in its current incarnation. It's main issue revolves around the fact that it hasn't been changed dramatically enough along with the other trees.