X-Pro 1 & Voigtlander
Depends how you shoot really.
Personally I live and die by MF, it's a whole element of photography that I love... I'm thinking that:
The X-Pro1 + some fast voigtlander glass will be amazing! I'm pumped about this idea and waiting to get my hands on a camera before ordering one.
The X lens shots I've seen look a bit too clinical to me - which is great for most. But I like a bit of character.
The X lens fly-by-wire focus doesn't sound very promising, nor the lack of a distance/dof scale.
MF at wide apertures is absolutely fine for the kind of work I shoot. I find a after a while a good camera + lens melts away and becomes an extension of your eye - you can just shoot shoot shoot without missing focus.
Despite what people on internet forums may say -- don't feel you need to stop down and widen your DOF on a fast lens simply to get focus, especially for portrait work... terrible advice...
Investing in m-mount glass makes more sense as I'm sure a FF mirrorless camera will hit the market in the next few years.