Ok.... So Photoshop is an 8-bit color depth program...

That certainly couldn't hurt to do that (scan at 16 bits per channel) and then downsample to 8-bits back in photoshop, but I'd have to look at results from both a standard 24-bit scan and a downsampled 48-bit scan to see if it was worth it.

Since you'd have that much more color information, the only thing I do know that would be affected is the speed of the scanning. If precise color wasn't completely important, I'd stick with 24-bit scanning, if something more accurate was desired, I'd only scan at 48-bit when absolutely necessary, just to save time scanning.