I know this is a very old thread but it makes interesting reading. No-one seems to mention bit-depth. When I started using digital I supplied 16-bit files but was told by an unwilling-to-modernise production man that the bit-depth was not sufficient.
It now seems that printers actually use 8-bit files so once you've done you converting to TIFF, supply as 8-bit files and you will get more files in the space. As I understand it, (and I may be wrong) bigger 16-bit files will simply be converted before printing.
It isn't clear to me if you are talking about bits-per-pixel or bits-per-color. There are 16 bit-per-pixel image formats that basically use 5 bits each for red, green & blue (so really only using 15 bits per pixel). The producting guy you mentioned may indeed have complained about that not being enough as 8 bits-per-pixel (for 24 bits per pixel) is the norm. This may be the 8-bit file the printer was talking about. There are also real 8 bit-per-pixel format but they typically (always?) use a colour table with up to 256 colors. Each 8-bit pixel then just specifies which color out of the table to use.