An RB is not a bad camera but if you really want digital there are moderately priced 35mm DSLR cameras out there that can match an RB67 film scan and there are also better MF film cameras then the RB.
The real issue is scanners. Don't think you can buy a v700 for $500 and get the most out of medium format. You need a Nikon 9000 or a drum scanner. Besides MF film is slow cumbersome and expensive. A V700 will do if you want to enlarge smaller sizes, but the dmax is very limited and that is an issue with slide film, and you have to way overscan. Still there is nothing else out there that will do what a V700 will at that level for $500. Its just not a professional level scanner.
An A850 for less that $2000 will run rings around a RB in time spent and almost match the resolution. I have had 2 RBs and 2 RZs and a variety of lenses and none of them were sharp enough to merit anything over a 2000 dpi drum scan.
The SD1 will most likely match or beat the A850.
I will say a 65mm floating element lens in an RZ is much sharper but never found one at a decent price.
A 2000 dpi drum scan of 670 film produces about 24mp.
If you are still set on medium format color film then I would suggest to buy the best and sharpest medium format film camera and scanner you can afford and shoot E100G.
The sharpest MF cameras I owned that were actually worth a 4000 dpi scan were the Mamiya 6 and 7 and the Rollei 6008I with 80mm lens.
All stunning performers and true 35mm type lens resolutions, especially the Rollei.
There are a few others too hassy etc. Never owned a hassy though.
Buy a Rollei 6008I and add a few lenses to the cost of a Nikon 9000 and you will be at about $5000+.
All that said, I do prefer film for B+W, but still to get the highest resolution and sharpest lenses in medium format it takes a lot of $
I was drooling over the new Pentax 645D & Hasslebald H4D, then i realised they just use 1 layer Beyer.
I did a bit more googling & found in 2011, Hassleblad are hoping to move away from Beyer limitations by introduction their "multishot" which is still 1 layer but captures colour information more like Foveon.
I think i will save myself £10k & get a film Mamiya RB67 Pro.
I hope one day Sigma can bring out an MF Foveon.
Mebe Hassleblad should talk to Sigma about licensing Foveon.
Meanwhile the SD1 will give the depth only a 3 layer sensor can give.