When I saw the images, I reacted the same way I had when the 7Artisans 28mm f/5.6 come out: No advantage over the Voigtländer in terms of size (at least not a crucial one), so, no real reason not to go for the most desirable option. Voigtländer has knocked it out of the park with the Ultron 28mm f/2 II. The TTArtisan is tiny - a little expensive for what it is on the whole, but it's well made, looks the part and takes nice images (not perfect, just nice).
What doesn't get mentioned a lot: The
old Voigtländer Ultron 28mm f/2 for M mount is a really good lens, too. Not as small and optically fantastic as its successor, but still enjoyable, with very nice rendering, good colour and sharpness. If you can put up with a slightly bigger lens, it's a good choice. Mine practically lives on my M8 - it's a "match made in heaven" ...
@Brian Great stuff! Unbeatable for the price, too. I'll say here that the Elmar-M 135mm f/4 is another affordable gem. I've never seen the Hector "in the flesh" - how does it compare in terms of size and weight?
M.