I too like my 4870 which I purchased new approx. seven or so years ago. I think the scanning software could be an issue if what you are looking for is no longer available. I'm using SilverFast Studio and still use a G5 with 10.5.8 and PS CS4. Since it doesn't have the Intel chip a I am able to do what I need with it, I haven't found a reason to have the expense of changing. I scan medium and large format negatives so that also makes a difference. I get excellent scans so if the price is right you won't go wrong IMO.
That could be a great deal. At this age, the scanner probably really needs the fog cleaned off the underside of the glass so I would recommend opening it up and cleaning it after you have tested it to make sure it is working correctly.
worth a read even if you are not intending to do it. I've cleaned my Nikon LS-4000 mirror and made a HUGE difference to contrast the mirror needs much MUCH more careful treatment than does the glass on the scanner.
Heck if you're intending to use it for film only I would not even put the glass back in (and devise a support for the film holders out of hobby plastics)