And stealth cannot be an excuse to not giving sins tweaks. In pvp stealth is used mostly to get into melee range without getting hammered along the way. You know another melee class that can do the same? Yeah, warriors with charge. Their jump even allowed them to switch targets instantly (best for melee train assist) and on top of that it allows to jump on the platforms where sin should run around to get to (for example get back instantly after being pushed from the platform).
Combat stealth? Yeah, marauders got that too.
So currently stealth brings nothing to pvp table that marauders did not already. I see no excuse
for sins to not being buffed to the marauders level of survivability and burst/sustain dps.
Mara stealth != sin stealth (sin combat stealth takes you out of combat and lasts longer than 4 seconds and lets you sap). Mara charge != sin stealth (sin stealth lets you sneak to the back of a team and start hitting a healer - maras that charge to the back of an enemy team also get targeted by everyone on that team while they're getting there and they usually have a nice amount of cc waiting when they land - also, snipers and invisible targets can't be charged).
I like that you mention platforms - sins can knock anyone off of platforms. They can go invis, wait for someone or several someones to walk into position and kb. In HB, the aoe kb is far more valuable than charge most of the time. If your teammates hang out on the ledge of their pit while the ball carrier is in the pit I can't help you. In many cases, in at least half the wzs, kbs can be used for 1-shot kills. Charge isn't useless of course, but kbs + stealth + speed (and some of their dcds and the pull) make sins the best class for hb. That's not me saying they're the only useful class; chargers and scamperers are useful too, but in my experience hb has almost always been won by the team with the most sins unless it's a premade vs a non-premade.