The first thing you should do is figure out how much movement you will need for your product and architecture work and what range of lenses. The RZ has a tilt shit adapter that you can mount most of the lenses on and do your product and food photography with, but it will have less tilt and movement than a more dedicated solution. It might be good enough but I never used one on my RZii so can't say. Also for architecture you will likely not be able to get wide enough with the RZ lenses and or may have trouble focusing out to infinity with the them on the tilt shift adapter. You might be able to accomplish what you want with a DSLR and one of their t/s lenses such as the canon 90mm TSE which is excellent but again the amount of movement is limited. Same goes for using something like the Mirex adapter or Zoerk adapter - you can get a bit more movement than the canonikon lenses but maybe not enough. You could employ one of the cambo X2 or Horseman View camera adapters with enlarging lenses which are very high quality and very inexpensive.
If you need the movement, then none of the traditional MF platforms is going to be adequate except for the Fuji 680. You can mount both DSLR's and Digital backs to all of the studio cameras such as the sinar, X-Act2, cambo, etc but the issue you'll find is that the DSLR's are hindered by two things - the deep mirror box which will often shadow the sensor with lots of movement and second the ability to employ wider optics since the flange to sensor is already 45+mm and you'll have an adapter and a bunch of other stuff like the shape of the body limiting how close you can mount it to the lensboard. I've had my 5D2 and a friends D800E on both my cambo X-2 and Rollei X-Act2 and this seems to the issues that cropped up. For tilt, and close up work with longer lenses this shouldn't be an issue DSLR's. It's hard to beat a digital back on a tech or view camera in the studio though. You'll have all the options available in movement and focal range. For the architecture where you might not be able to tether to a laptop, the canon and a set of wide TSE ii lenses is pretty good, but the tech camera would give you more movement. 680 might work okay here too.
That said, the color for food and product photography will be superior with a MFDB mounted to a view camera or something like the Fuji gx 680 which does have enough movement to work. One drawback to MFDB's will be possible lens color casts which you can get with movements. The older backs didn't suffer as much from this since they had larger pixels, and it is easy to fix by shooting and applying a LCC white frame, however its another step in the workflow. Fred will argue until he's made us all sick and then some, that DSLR's are better but since I've used both, my feeling is even the older MFDB backs can produce images with superior color out of the box and with more depth to them. The only food photographers I know personally use multishot backs on the Fuji 680. Some of the older multishot backs are getting really cheap too. A lot of architecture shooters are getting along great with the Canon since their 2nd generation wide T/S lenses are great, but many also use a digital back and a tech camera of some kind or another.
btw - Fred has written that the live view on the MFDB is not great, but he's probably never shot one tethered to a laptop or desktop computer before. The live view even on seriously old MFDB can be great when tethered. Hasselblad/imacon backs have even audible feedback on the focus. You select the point you want to focus on and adjust focus while listening to it tell you if you are getting sharper or not. The live view on my Leaf is quite excellent.
Where Fred and I agree is on the 680 which might suit you, but I think it only goes as wide as 50mm which might not be wide enough for architecture, but you can shift stitch with it I guess. Much easier to stitch moving the sensor than moving the lens like on the fuji but it still works.