agree with pretty much everything already said.....I have both and probably use the 907 slightly more but there are some things I would not try it.....and coming from a Leica one might be used to doing these things....
not tethered I shoot wide angle (21,30, some 45P) with the 907....unless I am on a tripod I use AF because MF is almost impossible, peaking is way to loose and the distance scale does not reflect f stop range....and there is no way to focus on the rear LCD (for me).....using AF pretty much means locked down subject (no people) .....
I use the 907 for studio portrait or people only if I have a constant distance (then I use MQ and a dialed in focus distance) tethered my digitech sees focus problems.....
architecture,....landscapes,....I prefer the 907 and I use AF.....
for anything moving (subject or myself with subject) and longer lens I prefer the X1DII.....in MF, I have no problem with the EVF....
as you can see the X1DII can do pretty much everything the 907 can, but not the other way around.....overall I prefer the 907 but it would not work for me as my only body....
I don't shoot on V system or tech cameras, it is definitely something to keep in mind as well, I know there are adapters for the X1DII but the CVFII is a much better choice if you want to go that way.....
a friend just bought into the system and I recommended getting the X1DII (over the 907) it is cheaper and more flexible, lenses aren't cheap, he is spending his money there first....I know he will get a second/back up body at some point, it will probably be a 907 at that point....I think that makes the most sense.....
a way to save some money is to get the X1D used and then the 907 since the original X1D is limited when it comes to tethering, which can be done with the 907 anyway....and some people say that MF is actually easier with the older EVF.....