I have an R-D1 currently. I have had an M8 and M8.2. The M8 VF/RF is more robust and easier to see when in focus. The base length of the M8 is longer and I understand that this makes focusing with fast lenses easier, but I've never had a problem with the R-D1. The M8, lens for lens, will produce sharper output, but in real world situations it doesn't make much difference, that is, the R-D1 is sharp enough in any case. The R-D1 and S are limited to 2MB cards; the RD1X is not limited. The R-D1 buffer is very limited (3 shots), so if you like to shoot fast and a lot, you'll struggle. The R-D1 is definitely better at iso 1600 than the M8 and has a most pleasant "old school" rendering of colour. It also produces superb B&W via Epson Photo Raw. I like both cameras, but prefer the ergonomics and immediate access to key functions of the R-D1 as well as the wind on and reversible screen - I never shoot with it open. I replaced my M8.2 with a Fuji X100 (and a lot of change) and regularly go out with the Fuji and Epson, finding them complementary.