The M3 SS has slightly better eye-relief than the M3DS. The viewfinder eyepiece is slightly larger.
A Bessa R would be a great user body, and they are reasonable prices these days. The built-in meter is convenient.
I tell by cameras that I love them by loading them up and taking them out. Today was the Canon VI-T out for a hike in the woods with a 135/3.8 Tele-Colinar. The lens was in a box of "Ebay Stuff" for $12.