Originally Posted by jaimiepeeters
That's not inexpensive :O
Compared to what? A Leica M8 (even used) or Leica M9? Yes, it is inexpensive. The GXR plus Mount A12 plus the optional EVF costs less than a new Zeiss Ikon film rangefinder too. It costs about the same as a Sony NEX-7.
The two cameras are quite different. The X100 is at its heart an autofocus /single lens/ camera that has a hybrid optical/electronic viewfinder.
The GXR with the Mount A12 installed is a manual focus /interchangeable lens/ camera. It has good support for focusing lenses, and is arguably the best digital host for M lenses other than a Leica M8 or M9, although for some a NEX-5N also makes a terrific host for M lenses. The NEX-7 and Fuji X-Pro 1 are other options but carry a little baggage.
I used to own a X100; even though I used it extensively and have also used the Ricoh GXR for some time now, I would not be able to compare the two in a meaningful way.
With good lenses on the GXR, in general, you should be happy if not thrilled with the performance. I'm very pleased with how all my Zeiss lenses behave on the GXR. With lenses ranging from 18mm through 75mm, including the ZM50/2, without comparing even one other dimension of the two cameras I can declare the GXR a winner over the X100. For me that boon is flexibility.
For myself I found the fixed lens on the X100 both a boon and a curse. You can travel lighter and don't need to think about lens selection ever. But there are many times when I want a wider field of view, and sometimes when I want longer, and I want all of the above out of my every day carry camera.
Two different cameras. Both great. Ultimately the GXR will cost you more, because if you want a similar 35mm effective field of view, you'll need to consider a new lens in the range of 21 - 25mm.