I get the feeling that this thread should be on the alternative process sub forum…, but I’ll throw in my 25 cents and hopefully folks will find the information useful.

I have an Epson 4870. The differences between it and the 3200 can be boiled down to three points. Resolution, ICE and price.

1. The maximum optical resolution for the 4870 is 4800 dpi vs. 3200 dpi for the 3200. This is important when scanning film smaller than 4x5, because the extra resolution will be an advantage for higher quality output (especially oversize prints). If you just plan post images on the web, save your money. If you plan on other uses including printing images or oversize contact negatives, the higher quality will weigh in. Interestingly, when scanning 4x5 with the 4870, the scanner only permits a 16 bit scan up to 3200 dpi anyway (with a resulting file size of 1 gig!)
2. ICE adds quite a bit of time to the scanning process (a 45 minute 16 bit scan of a 4x5 piece of film becomes 5 hours), but it saves an inordinate amount of manual labor spotting out dust that is attracted to the film and scanner bed. With my computer, the scanner operates in the background, so the extra time is less of an issue. I also ease the pain by starting a scan just before heading off to bed, so that it is waiting for me in the morning.
3. Is ICE and increased resolution enough to justify a higher price? That depends on what your time is worth and what sort of budget you have. Regarding price, it is not necessary to purchase the PRO model of the 4870, which just includes more unnecessary software options. The standard EPSON driver that comes with the basic 4870 is a terrific program that is easy to use and produces wonderful scans.

Some final notes:
A dedicated film scanner will typically outperform a flatbed. So scanning your 35mm shouldn’t be factored into your decision if you have access to a film scanner.

Charles Cramer uses the 4870 to proof his 4x5 color negatives, a task he feels the scanner performs better than even the $65,000 TANGO for a variety of reasons. First, there is less apparent grain. Second, the software seems to generate more accurate colors from his negatives, and last, it is very convenient to drop a 4x5 negative into a film holder and plop it on a flatbed than wet-mount the same film for the TANGO. I will say, he still finds the TANGO superior for scanning transparency film, but notes the discernable gap in quality is narrowing daily with advances in consumer technology.

So as you consider the purchase, ask yourself what size film you will be scanning, what the intended use for the scan will be (web or print), if it is a print, how large will it be, and finally, how much is your time worth?