Thanks folks for the welcome, sorry it's been awhile since I checked in last.
For the past year I've been shooting the GXR system with only the Mount A12 (M mount) module as my primary camera system. I use a selection of Zeiss M mount lenses ranging from 18 through 50mm and one CV 75mm f/2.5 medium telephoto which gets effectively a little longer due to the 1.5X crop sensor.
As far as compact cameras I've found the Ricoh has about the best photographer-centric handling and menu system of any I've used. Prior to adopting the GXR I used the Fujifilm X100 extensively, and spent a couple months with the Sony NEX-5N.
In addition to handling well, the GXR Mount A16 was purpose built for M lenses, and, importantly, has no anti-alias filter. M glass really shines on this camera in ways that adapted M lenses on the NEX - while often terrific - can't quite meet.
The camera isn't perfect but it is close. Modernizing the sensor and updating the viewfinder are two frequently asked for updates from GXR users. Shot to shot time could be improved as could shot buffering.
Here's a snapshot of Vancouver ... had to run to catch this and run back to my double parked vehicle. Shot on the GXR with Zeiss ZM18mm (effectively 28mm field of view).
I'm happy to answer any questions about the GXR system you may have.