It depends on your situation. I know that answer is kind of vague but its the only answer you can really get.
I always try to keep at least 2 bars for breaker; its always going to come in handy. I don't rely on xray for damage, but I do rely on it for pressure and to finish off a round. I don't use EX for more damage, I use it for emergencies - like, if I think my smoke bomb isn't going to hit, I'll use EX instead (I main smoke by the way).