Hi, I have an IBM (AIX) server that has the CDROM mounted that way and it works fine. Those drives that were designed for that orientation have small "fingers" that can be used to guide the disc until the drawer closes. Once the drawer is closed, the disc is only supported by the center spindle, anyway. This server also has an Exabyte Mammoth tape drive and a floppy drive mounted the same way!
If our experience is any example, it works fine, so if everything else is a fit, go for it!
---Will