I went from an older Canon AE-1 with 3-4 lenses to a Mamiya 645E with comparable lenses...I haven't gone back to using the 35mm since. The only reservation I have is that the 645E model does not have a removable back like the 645 Pro TL. If I did it over again, I would get the Pro TL...or a Hasselblad...

Of coure, after a year of the 645, I then went to 4x5...it's been downhill ever since!!!