Off-center focus is what I live for. Perhaps an IQ back mated with a H5x would be the best solution. I'm a sucker for good design however, and the XF is pretty cool. However, if I'm not getting critical focus reliably when shooting people, it's basically an extremely expensive paperweight to me.
I was secretly hoping that Phase is just a software upgrade away from doing a bit of technical trickery to allow the sensor to achieve off-center focus, but I guess that's not in the cards.
I'm sure Phase will improve their product, but I don't think focus is easy enough so they can do it quickly or promise anything and be trusted.
The big problem with MF and even 35mm fullframe SLR AF is that even when there are multiple focus points, they end up clustered around the center of the frame. And an event, marriage or fashion shooter often has the face floating at one end of the frame. This limitation will disappear with mirrorless, but I don't think the XF can escape it. The other problem is that focus and recompose introduces some aliasing -a few inches of misfocus- at medium distance, but those few inches are really really perceptible in practice if you aren't @F8.
There is one product which does off-center focus and recompose well, and that's the Hassy, whatever its other qualities. That's why they can sell an F2.2 portrait lens.
You can ask around on this forum about that.
The newer Hassies (H4x, H5x) also work with the older Phase backs, and there are a bunch of those old backs around now. Maybe some forum member wants to share their experiences.
Of course a hetoregenous system means multiple batteries and warranties to contend with, and finger-pointing when it breaks - but there is probably a dealer here who would be prepared to stand by such a solution, and might even have something cheap in stock.
Maybe people with real world experience of the Hx-Phase combo could chime in?
Edmund