If you are doing mainly studio, product and food you should keep in mind the usefulness of tilt shift lenses.
Neither the RZ or the AFD offer that much in that area and the prices of the tilt shift lens o two they have are very expensive.
Many people are using Fuji gx680 cameras that have a full range of tilt shift lenses. Actually all the lenses are tilt shift.
From 50mm to 500mm.
The cameras can be found on ebay for very good prices.
Kapture group makes an adapter and control box that lets you use digital backs on it.
What is even more interesting is that they make a stitch adapter that lets you shoot two shots and do a very simple stitch.
This would give you a huge 43 to 44 MP file and capture an image capture area twice the size of the top of the line
backs . The stitch adapter also lets you take full advantage of the angle of view of the wide angles
On top of a straight two frame stitch you can also use lens shift to increase the capture area, but for distant subjects like landscape.
This will give you a straight easy to stitch panorama of about 52 MP of a virtual capture area of about 6x11.8
The lenses are outstanding and made at the time in the same plant that makes the Hasselblad H lenses.
The Kapture group adapter for single shot with the control box is about $ 800 new, but you will save a heap of money on lenses
and would have a full range of tilt shift lenses.
The Fuji system has some very nice viewfinder options that work very nicely with
the crop factor of using a digital back.
Regarding the Mamiya RZ it is also a nice option, but very limiter tilt shift options.
Regarding the lenses they are excellent and are plenty sharp to go even beyond a 22 MP back.
I owned both the RZ, AFD III, (phase One AF), DF and still shoot with the Fuji gx680.
Like many I found the AFD/DF to be problematic, but the RZ was a very reliable workhorse.
I would recommend the RZ over the AFD/DF. Lenses are very inexpensive and in some ways better.
IF you want more info on the GX680 send me a PM with your email and I can send you a system brochure and manuals I have scanned
Oh and one last thing. The RZ and the Fuji GX 680 are fantastic with film. The 6x7 or 6x8 negative size gives them a very nice true MF look
compared to 645 that back in the day was entry level MF.
Here is an example with the RZ:
and because we're on the internet a crop from the same negative (scanned with the relatively modest Epson v750)
EDIT: Close up crop of detail of the clothing removed as it seemed to bother someone.
Replaced with this detail... for everyone one who may be interested.
And here is an example shot with the Fuji gx680
Crop from the same image.