Christ! Just ignore G50, he can't actually respond to questions like an adult. FYI, D-VHS is not aimed at the same target audience, nor does it do the same job. D-VHS is a poor substitute for any DVD burner. And vice versa.
RAM is the most hard-drive-like of the rewritables. It is easily capable of recording one show while watching another, similar to a DVR. It would be my choice if more companies supported it. While more are starting to, that doesn't help older machines that are incompatible. Of course, there's little guarantee that either RW format is compatible with your machine, either.
The problem with all these formats is compatibility with other machines that you might want to play your burned DVDs on. RAM is more or less guaranteed to be compatible, IF the machine says it plays RAM discs. Machines that claim to play -RW or +RW sometimes don't actually play all of them due to incompatibility with the burning software or specific brands of blank discs.
It's a big ol' mess. Some places for some info:
www.dvdrhelp.comwww.dvdplusrw.orgwww.dvdrw.comwww.dvdforum.com