Hi,
I know the Leaf systems rather well and own the AptusII7 at the moment and shot on some demos with the AptusII10.
The AptusII7 is an amazing back, it has a very nice quality and somehow I see a bit more depth in the images compared to the Aptus22.
Personally I don't want a crop (or at least as small as possible) so I mainly focus on the Aptus series that has the larger sensors.
The AptusII10 is indeed a 3:2 sensor which has to fit your style.
I absolulty love the quality you get from the AptusII 10, portraits on f16 are still very sharp.
The real difference is the aspect ratio.
PERSONALLY I love the 4:3 format but we have a problem printing that over here because the format of the A papers are more in the area of 3:2 than 4:3 so when shooting I have to remember to leave a bit space to crop later.
However this is hardly ever a problem, and also with 3:2 some cropping is done.
You have MORE than enough resolution with both backs to crop and with the AptusII 10 you can without a problem crop to 4:3 of course with different helpful options.
If I had to choose it would be difficult.
Although I absolulty love the AptusII10 the price range of the AptusII7 is much more attractive and the AptusII7 is faster in transfer to the mac/pc.
So it would depend on what you shoot, for a landscape shooter I think you will be more than happy with the AptusII10, for portrait and fashion I "think" the AptusII7 is maybe the best choice also due to the format.