QTR-Quadtone RIP

Actually, resolution is one aspect of scanning; usually you must take in account the DMax offered by the scanner. I can't help you with medium format film since I use two "flatbed" scanners (not the best choice for films and negatives).

I use a Nikon Super Coolscan 5000ED for 35mm and at 4000 dpi and a DMax of 4.0, the results are great. Since I have more than 100,000 slides, and almost the same amount of B&W negs, a good scanner is the only way to go. The output files (Nikon, at 16-bits, are around 140 Mb). The good thing was that the Nikon driver (free) did a wonderful job (if you stayed away from the "Ice" use); the bad thing is that Nikon stopped the upgrading of the driver and, if you're with a newer system, it is not possible to use the driver.

For that, I bought a VueScan license and, believe it or not, at the price they ask, it's a bargain. My "old" scanner is working perfectly with my newer system (although I kind of lost the RAW attributes ; I must say that VueScan is offering a way of using it but my laziness kept me on the "tiff" side). Moreover, the license "sees" my two other scanners perfectly; so although a bit slower, I can use my "new" Epson V850 Pro and my "old" Microtek Scanmaker i800 (Both with a DMax 0f 4.0).

If you can find a "used" CoolScan (saw one at 400$ US on eBay), it could do the job with all your 35mm tasks.

One word about Silverfast; the license is "hooked" to one product. My V850 came with a "free" license for that scanner and, after trying different settings, I was not impress. The price is quite steep and, for me, overpriced. Sure they are "pro" profiles; that must do a good job but, as a matter of fact, the Epson driver delivered perfectly defined scans out of flat documents. As for "negatives" and "slides", some jagged edges are proprietary of a flatbed scanners. Although I wrote to Epson, the "support" is not so great. You'll have to call to see if they can help you. For me, I never called back, the answers were a bit obscure.

So, at the end. I would say that a resolution of 4000 dpi, with a DMax of at least 4.0 (the more the better- maybe the multi-scanning of Silverfast helps) could do the job. For an example, the Imacon scanner, (rotary one) has a 4.6 Dmax. It is surely out of your ballpark for the price, but, since these seem the best scanners out there you can see that a medium format resolution is around 3200 dpi. Must be the DMax!