i changed schools after arnd 40hrs and it wasnt a prob i just got my training record and took it to the new school,
i changed aircraft 3 times during my training and it was fine i went to another airfield so after a couple of hrs to get used to the new procedures i was happy with the new plane so it didnt make much difference, maybe helped a bit as i am happy to try out new planes and maybe if all my training had been on one type i would have been a bit nervous to change after 100 or so hrs
if you do change types thou dont try and do it while having a normal lesson as i did, the crosswind was outside limits for my normal type so we just took something else Major Mistake, i was totally over my head trying to land at Cardiff in an unfamiliar type,
good luck anyway hope u find a school that suits u