Hm, I'm thinking I'll take a few lenses to the shop and try it out, take some sample images home as well. I've only handled a X Pro1 once, back when it was first released. It was nice, but I felt like I wanted to manually focus the lenses, haha. Jpegs at ISO 3200 were so good, I thought they were at ISO400 or lower. X-Trans might bother me if I can't get a decent raw converter, though (Windows). I'm running Lightroom 4.4 for almost everything.
I've just read that M lenses can get smeary corners with the X-Pro1, which may bother me. If anything, I suspect I'm trying to justify an urge to get into the X system. Start with M lenses so I don't have to spend much money. Then maybe a X lens. Or two. Then the slippery slope begins.