I have the Mamiya 6MF variant and could not be happier. I have all three lenses, they are spectacular. I have never had any issue with anything breaking (knock wood). I think some of the fragility issues were addressed when they released the MF version.

Some complain about the extra marks in the viewfinder of the MF variant. Personally I like them, I use them as I would a grid.

I find that you can trust the framing lines (which adjust per lens). The only time I've ever been misaligned was when trying to shoot something closer than closest focus (filling the lens with a grey card for film speed testing). But that is outside the scope of the design...

The two things you will need to adjust to are using the focus patch, and perhaps lack of a depth of field preview capability. You'll get over the latter, and only use will tell you if you can work with the former.

The camera is extremely light and compact for MF. It is smaller and lighter than my Nikon SLR, very nice for hiking, and very, very quiet.