I currently have an Epson 3200 and I'm contemplating upgrading. I do b/w and color negative photography exclusively so D-Max is not really a limiting factor for me. My tests show that I get 28-30 lp/mm effective resolution, which is what a perfect scanner sampling at 1422 to 1524 spi would deliver. Ted Harris has said that the V700, scanning at 3200, which is probably how I would use it, delivers at best just under 2000 spi. He and others also say that used this way it doesn't do as well as the Epson 4990. So it would appear that the 4990 might be the better buy. But I have some further questions which Ted or someone else might be able to answer.
First, it was reported by Roger Clark that he couldn't scan a full 4 x 5 frame with the Epson 4990 at 48 bit color depth and 3200 spi. This seemed to be a problem inherent in the scanner hardware/firmware as confirmed by Ed Hamrick, who makes Vuescan. It worked fine at 2400 ppi or 3200 spi at 24 bit color depth. Second, most reports suggest that the 4990 yields an effective resolution of between 30 and 34 lp/mm, which translates to 1524 to 1727 spi. Roger Clark reported signficantly better results, but otherwise I haven't seen anything suggesting the 4990 could approach 2000 spi. Finally, it does appear that there is considerable variation in what is reported about these scanners. Some of this has to do with technique and how it is measured. I think Ted Harris's estimates are probably the most reliable in this respect. But, there may also be signficant variation in how individual units behave.
Can anyone comment further on any of these points?