Yeah, Stim boosts your health a little bit. Not a big fan of those kinds of abilities, but since you can only use it once in one life, it's hardly worth it.
Wait, Stim is like...juggernaut??
I thought it just regenerated your health faster.
I'd be careful with exo buffs. Some abilities like invisibility would be used more for camping, while others like Overclock would make the speed of the game even more insane. It definitely feels that most people will forgo exo abilities, but they need to be adjusted individually, because I think they add an interesting twist to the gameplay.
That's why, while all the Exo Abilities are pretty much not worth their point value in the Pick 13 system, at least they aren't completely overpowered. But a part of me wishes these new abilities added more to the experience than they currently do, but I have no idea what the right way to go about making them more meaningful would be while maintaining some semblance of balance.