I made an adaptor so that I could use the Cambo stitching adapter on my Ebony 45S.
My observation is that its possible to make great pictures with this, but focussing is much harder than with 5x4, that little 645 area is tricky. However the Cambo stitching adapter has a built in loupe which works quite well. I don't think that this set up would be able to focus at infinity with anything wider than a 55 and I think its already getting hard to get focus, movements with the 72XL.
The better LF lenses can produce good results. I have compared my 72XL and my new digitar 72L and while the 72L is stellar, the results from the 72XL are really not bad. Also I have had very good results from my 150mm Schneider.
It all depends on your goals, subject matter, time envelope.
The biggest benefit seems to come with stitching. This is because of the huge image circle of the film lenses. With the A75 I end up with a 58megapixel equivalent file. Even with the slightly softer look of the 72XL that will make a print of fantastic detail at say 72" wide, if you can afford to print and mount it :-) Files from decent print lenses also sharpen up nicely. With digital lenses I tend not to sharpen at all.
I use the Cambo Wide and Mamiya AFD for my commercial work, and mainly keep the Ebony for personal work. The jury is still out whether its worth it or not. I'm really not sure. The main thing is that you lose the LF look when you switch to the small chip. Its a different palette. So far I've found that some of the coolest looks come with a Schneider Xenotar f2.8 105.
I have to admit, that its only gear fetishism keeping me going with this, I haven't hit the sweet spot yet, and maybe it doesn't exist. If I don't crack it within the next couple of months I will be going back to 5x4 film with the Ebony for my personal work.