Based on my own experiences and from what I've read from other owners, I think the SD IV is a hit or miss product and I would not recommend it. Mine worked well for the first few months, under what I would call moderate use. It eventually developed a banding issue (grey-white-black banding in b&w and blue-red-green-etc. banding in color). I sent it to Konica-Minolta in NJ, where it spent a month in repairs. It came back, worked for a few months, then was hobbled somewhat again (and outside the warranty period).
Currently, my SD IV cannot scan at full 3200 dpi res. without banding. Using VueScan, I set it at 1600 and it does a credible job with b&w film (in fact, I like its b&w performance). This setting is fine for printing up to 8x10. As for color, I have never been able to adjust the scanner's/software's settings so that I get a clean color scan. I have to do too much post-processing to get the colors right.
I have been under the impression that my SD IV's color performance was par for the course for most scanners, but recently I got a Nikon CoolScan 5000, and it has been a revelation. This scanner is much more expensive ($979 at B&H, and usually out of stock), but as a point of comparison I got an absolutely gorgeous color scan on my first try, no post-processing required. As Gabriel noted, the SD IV does not have digital ICE, so it requires spotting (esp. w/ color negs, which inevitably get dusty in handling, even at pro shops), thus requiring more time in post-processing.
If you are going to do mainly b&w, I might say the SD IV is a good scanner, especially if you can find one at a good price. In my opinion, $250 is too high, considering you will have a hard time servicing it should it break down. Up until a few months ago, B&H had the SD IV for $220 new. I do not know what is a good price for a used scanner, given they are now pretty rare. I would strongly caution that if you buy used you should buy from somone you can trust and who will give you a 7-day return warranty.
