With the next version having variable (mostly 0 for these) slot devices a lot can be done with ship enhancements. George if any of these will not work please tell us.
+1 slot (if taking -1 slots works, I hope it does)
0 slot reactor kind of like the default reactor now (you could even have it if they are stupid enough to unequip the reactor they have no power and will die quickly like should happen)
various other things you can do with devices now but you don't have to worry about them being unequipped and getting a free slot
these will depend if you can get them to stack and I don't know the answer to that.
things we don't have access to (would be nice if a device could change these so we have have ship enhancements for these things too)
mass (this is really minor)