Thanks for your input everyone. It looks like it will probably be the M7 for me, at least for now! I go everywhere by foot/bike/public transportation both at home and when I travel, so weight and portability is the biggest factor, and it looks like it wins hands down. I do like the range of lenses and close up focusing of the Pentax, but it's not critical to my shooting, and I have other systems that can do that anyway.
Only slightly lighter, but I've heard people say the ergonomics are much improved.
Originally Posted by Alan Gales
When you say you want something that comes as a system, I'm wondering what constitutes a system for you. Both are systems, but the Pentax has more options in the way of lenses, viewfinders, grip, focus lever etc.
As others say, the Pentax is not really designed for handheld work even though the ver.II is quite a bit lighter.
The Mamiya, on the other hand, is perfect for hand held work.
If you just want 6x7 and don't need interchangeable lenses I would concur with TimVance about the Fuji GF670. It is fabulous and incredibly compact and portable.