I voted R2A, purely for the AE. Personally, I would not worry about 1/2000th of a second, you can always stop down, get an ND filter, or just over expose by one stop.
If you're shooting negative film, you can likely do without a meter, but slide film you likely cannot.
The M3 is obviously a legend, and a very pretty camera, but for actually taking photos, unless that Leica build means everything to you, then the Bessa is likely better for everyday use.
I'd second the opinion to use the M3 for a bit, see how you go, and if you find a meterless camera a pain (I know I would for an every day camera), get the R2A and use your Summicron on it.
If you love the M3, you can get a tiny Voigtlander meter to put in the hotshoe, which will make things easier I imagine.