There's a lot more to digital imaging than resolution. The 4870 is still a flatbed - but should do very well for a lot of things. If you were using larger film sizes and wanted proofs, then it would be a good choice. Also for scanning prints, which is usually not a good idea unless you're talking about expertly printed B&W darkroom work.
That's getting close to the price of a Coolscan V which would still be my choice. A used Coolscan IV would be good too - you may even find a new one at a bargain somewhere because the V is pretty new. The IV doesn't have the current version of digital ICE, but still has the basics of it.