Stephen, I had the RD-1, and now the G1. I have been using some Zeiss, CV, and Leitz glass on the G1, and I have to say, I like the files using these lenses on the RD-1 as opposed to the G1. I have found the Panasonic lenses are undoubtedly the best option for the G1. I was hoping to see some differences using rangefinder glass, and I do not notice any differences over the Panasonic glass with the chip in the G1. As a matter of fact, I have been disappointed.
For me, Leitz, CV, and Zeiss glass are best on the RD-1 and M8.