This looks potentially interesting - particularly for 5x7 and 8x10 users. While this scanner isn't likely to replace drum scans when that level of quality is required, it may well be perfectly suitable for other, less-demanding tasks (e.g. web versions).
One side benefit of the 8x10 film scan area is for making scans of full PrintFile pages of smaller formats. While not "real" contact prints, they're quick and useful for reference purposes. I'm currently using an old Epson Expression 800 Pro for that purpose, along with a 3200 for 4x5 and a Polaroid Sprintscan 120 for 35mm and 120. Whether the 4990 might replace that depends on how they've arranged the 8x10 unit. If it's a drawer-like arrangement, similar to some of the older combo units, it likely wouldn't take the acetate sheets.