Most times when a bp is raised eating F/t they are pretty good about continuing toward feeding f/t throughout their life. Some differences are that sometimes when they eat mice they have a hard time switching to rats and a few times they can go off feeding for a short period as they mature and tend to do it in the winter months.
I think if you have a ball python with a good feed response they shouldn't switch from frozen thawed once acclimated to it.