I find myself doing cost-time analysis all the time. It applies to more situations than just CD-RW units, but it helped me rationalize my decision. It might help you, too. If you answer yes, then the only question left is whether you're willing to spend any money at all. Blank rewritable CD's cost about the same as a blank tape, but the price is still falling.
Tape drives are usually slow, too.
A 2x writer can burn about 17.5 meg per minute. You'll be disappointed to learn that CD-RW drives will save you money the long run. Do the math. Either way, Iomega loses.