If you are using a barrel kit with different bore sizes, and sizing your barrel to be a nice snug fit to your paint, then don't take out more than one brand of paint, as small variations between brands may be enough to cause barrel breaks, when you have sized for one brand of ball initially.
If you want to start mixing different makes/models of paintball I recommend overboring and using a 0.691 or 0.693 barrel/barrel back/bore size and that should mean next to no barrel breaks for pretty much all paintballs out there at the expense of your accuracy to one degree or another.