Can't answer your first question as I sold my R2 body - although I seem to recall all sorts of dire warnings about attempting to collapse any lens on a Bessa.
As for the lens quality, I have one on my IIIf, it's a nice lens, although it does tend to get a little soft wide open.
If you search the gallery using "Summitar" in "all fields" as options, you get 18 pics that give a pretty good idea of what it's capable of.
Big caveat with all Leitz lenses of around that vintage is that they are now quite old, and also they scratched really easily - so it can be pretty rare to find one without some cleaning scratches. But it takes a lot of cleaning scratches to affect the picture....
tim
