Can one focus an R Leica or any SLR any faster?
In all honesty, yes. I can focus my Nikon FE2's faster than my M6 0.85 – even after the MP optics were installed.
And it's not a matter of experience. I've been using an M6 as my primary camera since 1998, and the first manual-focus camera I ever used was my dad's M3.
But the M has other advantages: with a lens mounted it's noticeably smaller and substantially quieter than the Nikons, the lenses (especially 35mm FL) are noticeably better at wider apertures. In addition, for street work I strongly prefer a viewfinder where everything is in focus, and I often scale focus by touch. There, the M is much better (due to the small size of the lenses, and the fact that the VF view does
not change with the taking lens's focus). I find that the
overall speed of operation is not slower than the FE2's, and overall my hit rate is higher with the RF than with the SLR.
But faster focusing? No way, not for me.
It's a terrible error to start shooting rangefinder with a lens that has a DoF about the thickness of a piece of paper. Really, that calls for serious expertise. The Noctilux is not a beginner's setup – and the M9 without a VF magnifier really doesn't have an accurate enough RF to nail focus with that lens, anyway.
It's like getting a
Moto GP bike as your first motorcycle. Even for an expert, one wrong twitch and you're face down in the asphalt.