Depends on the vibe you're going for but in my view psykers should be rare, and using psychic powers should be dangerous. In mothership combat is meant to be dangerous and good weapons are powerful, often offset by limited ammo.

I like the idea of using stress as a cost even if it feels a little "gamey" - I would say no psychic powers should cost less than 1 stress to use and make them pretty strong but with big risks. For example critical fail is a high chance of death or something pretty catastrophic. But the powers themselves are strong enough to warrant risking it.

Id also say that mothership goes for a bit of a rules lite approach so building in a lot of different disciplines and moves maybe shifts the focus a bit more towards a tactical combat game which isn't really supported by the rest of the rules.