I have the Epson 4870. Batch scanning is nice. It would be nicer with a 4990 because it can do bigger batches.
As for the film being not flat, a scanner is not an enlarger. It does not project an image. Light passes through the film as a parallel beam so not-flat does not mean not-focused. It might introduce a slight geomeric distortion but that would be very slight.
Digital ICE is also __very__ slow. It can take hours to run ICE on a batch on film on an Epson flatbed scanner. But it really does work.
ICE was developed by Kodak and is licensed to the various scanner makers. However each implements the technology differently. There are some settings. Epson chooses to "go easy" and maybe miss some dust but never clone out details Others may be more agressive.
Read more about ICE on kodak's web site.