i don't know anything about digital backs though?
Then you need to read every thread on the forum - then you will know too much !
Your 'problem' in you first post is time saving - so save that time another way - pay someone to do your retouching !
The whole digicam thing is a minefield
The MF costs are stupid - but so are the costs of upgrading a DSLR every year if you feel that need
I own a D3 which is an amazing camera to use it is so fast and flexible the AF is great, the live view fantastic there are loads of cheap lenses and the ISO amazing
I own an H1, the AF is poor, the live view non existant, the range of lenses poor, the lenses are a rip off and my 22mp back is only good for 100 ISO max so its tripod time all the time indoors
but the files from my 22mp back are more than twice as good as the D3
I own a sinar P2 I have never really used it (on location) because shooting with my H1 and correcting the perspective is so much faster and easier
Every bit of kit there are pros and cons
Canons may be OK, but they have a wierd reputation for thier wide lenses, the AA filter makes the files soft compared to a MF back of the sime size and you cant clean the sensor easily
Hassies - no shift lens - great camera expensive
Mamiya - cheap but crap shutter flash synch (there is a shift lens from the 80s) and the 28mm lense is so expensive you can almost buy a cambo and a better lens for the price
Rollei - Expensive no wide or shift
Mirrorless cameras (alpa/horseman/cambo) - great lenses - very expensive and slow to use
What would I recomend?
I have no idea every solution has an up and a down side