I'm just speaking for myself here, but I've never been particularly drawn to the Mamiya TLRs precisely *because* of the interchangeable lenses. They seem sort of at odds with the "light, straightforward, no complications" gestalt of the TLR concept, and I do the vast majority of my shooting with a normal lens anyway. That's not to say they aren't wonderful cameras---by all accounts they are---but it seems to me like a strange direction to go with a TLR specifically.