I've never kept or looked into keeping mice, so I wouldn't be the expert on them. I've heard that nutritionally, there isn't really a different gram for gram, and the only reason people will recommend rats over mice is due to BP's being picky eaters and sometimes not wanting to switch feeders (which means many many mice where one rat would be more convenient). I'm only breeding rats right now, mostly because of the size snakes I'm looking to feed (3 small enough to eat mice or rat pinks/pups, 5 on small to large rats), and the baby rats work well enough for feeding my smaller snakes. If you have the space for both and you don't think your BP's will be too picky about switching food, I would say go for it, but if you have to pick one or the other I'd say go rats.