"I'm impressed by many of Cosina Voigtlander's rangefinder camera lenses - so much so that I own several of them and use them often. Some of these models are really exceptional - not only with respect to their modest cost but at any cost. But, to be quite honest, I see focus shift more often in certain more recent CV lens designs than I do in most lenses made by Zeiss and Leica. Many older CV designs like - for example - the CV 28/1.9 Ultron, 35/1.2 Nokton (Version I), 35/1.7 Ultron, 50/1.5 Nokton (all aspherical models, interestingly) have shown almost no visible focus shift in my resolution tests. I haven't yet tested the new version of the CV 35/1.2 Nokton but it is an aspherical design and I wouldn't be surprised if it did not show any problematic focus shift. But I have seen notable focus shift (though in varying degrees) with the CV 28/2.0, 35/1.4 Nokton, 40/1.4 Nokton, 50/1.1 Nokton and 50/2.0 Heliars (both versions). That doesn't mean that these are bad lenses (they certainly are not) but their focus shift is worth knowing about.
The CV 28/2.0, for example, is a wonderfully compact and affordable lens that performs well in many respects. But to use it one must accept some focus shift."
Focus shift isn't an issue with NEX unless you focus wide open and then stop down to shoot. With mirrorless cameras, I tend to just focus at the f-numbers I plan to shoot at, so there's never a focus shift issue.
Even with a film rangefinder, I wasn't troubled much by focus shift with the 35/1.4. It was there, but irrelevant to me from a practical standpoint. Lots of people say the same about the other lenses Sean mentioned.