i have comparision prints made on 2450 and 4990 using very sharp colornegatives made with rotating panoramic camera. only center of the lens is used.
comparing 20x-print of 2450 with 12x of 4990 shows me that 12-15x enlargements can be made. 2450 is said to resolve 8x as maximum.
i didnt use the best possible filmholder which should be scanmax wet-scan-holder or at least dough fishers mf-holder with antinewton-glass.
negative was just sitting on the scanner-glass.
details of 0.01mm on the film are clearly resolved. maybe 20x prints could be possible with 4990.
btw: there is a scanmax-discussion-group at yahoo:
scanning in general and epson-scanners plus using scanmax.
http://groups.yahoo.com/group/SCANMAX/