Fast and wide adapted RF lens reviews

Having just sold off some of my medium format lenses, I'm now looking at options for the NEX(t) camera system. I am struggling with a decision in this front. I'd like to go the compact RF route for size and elegance, but am concerned about colour shift and vignetting in the corners, at least at some wider focal lengths.

I could go with SLR lenses - I have a Zeiss 1.7 50mm, and some Yashica glass, and others can be had not too expensively - and, I think, avoid vignetting when wide open and colour shifts.

In the longer lenses I have a feeling I could go with almost anything based on the reading I've done. In the shorter focal lengths, I'm not so sure. Is there a good compactish solution somewhere in the 21 - 28mm range, with a preference towards the 21mm end of the scale? A Zeiss ZM 25mm Biogon f/2.8 seems almost perfect although who knows what it will do when mated with the NEX-7, the other prong of my dilemma.

Travis has me looking at the Voigtlander lenses of course but that colour shift issue on the wider end has me stalled and I'm tending to want something a little wider than the 28mm.

Any thoughts folks?

While I hate analysis paralysis it is part of the program I've bought into going with the next so I might as well enjoy it. On the plus side, I get to shop for a new lens and that is always interesting and sometimes even rewarding.