The F6 is really pretty amazing -- I just wish it was in R mount...I just love the Nikon bodies, but the lenses just don't really impress me...the problem with spending years shooting Leica, Schneider, Zeiss and Mamiya...and for whatever reason the ZF lenses have not really won me over either. As amazing as the F6 is, I think if you want to shoot R lenses, the R8 or R9 are hard to beat. They are excellent cameras, and the metering is not quite matrix, but it is very reliable (all three -- multi-segment, center and spot). For its part, the F6 feels nicer in the hand (my hands anyway), and of course it is autofocus, auto advance, has more sophisticated metering and an endless array of custom functions and features. It is also much smaller than the R9 with a motor drive.
The F6 has a nice data imprinting feature too. It puts the shooting information in between the frames. It works really well, you just have to remember not to replace the film halfway through the roll if you are in the habit of doing so -- as you advance past the shots you have already made, it will imprint the data over the already shot frames.
And yes, you can enter the focal length and aperture information for R lenses, but they are still stop down metered, so I am not sure they will matrix meter properly other than wide open.