Hi Peter,
I too want to hear about sinar's white frame implementation!
I shot my P65+ on a Cambo RS with the 40 HR in a T/S mount. Re your first point: Focus was no more difficult than with any other back -- bottom line is you need to nail it with anything you use, period. Anybody tells you different, like that a larger pixel is more forgiving for focus, send them my way and I'll straighten them out -- at this level, they are all critical
.
Re your point two: All the smaller pixel means in relation to f-stop is you hit a diffraction limit earlier. However, you only see this IF YOU COMPARE FILES AT THE PIXEL LEVEL. If you compare files at the same final sensor magnification size, there is essentially no visible difference. Moreover, I shoot my P65+ at f16 a LOT of the time, and frankly have ZERO issues with diffraction. At f22 I start to see some obvious diffraction issues (and frankly saw them with my P45+ too) but they remain small enough that in many cases the added DoF from the extra stop is more of a benefit than the slight loss of accutance -- a loss that is very difficult to see in a print.
Cheers,