The Iomega one works fine Have burnt 3.4GB liao onto a DVD+RW using my slow Celeron 566.
I'm not too sure of the benefits of being able to burn onto both types of media though.... pricewise, the media cost almost identical but the "dual-format" drive usually cost at least $100 more than "single format" type.
Btw, Verbatim DVD+RW's are going for ~$9 per piece at the PC Show. Is this a good price? TDK ones are going for $18 a piece