my PS2 only plays -R. and my dvd player doesnt give a damn what u put in it lol. add that to the fact that DVD-R are actually cheaper, i would go for them instead.
if ur going for Ps2 backups, DVD-R is the best.
personally, i would get a dual format burner. burn DVD-R and DVD+RW. DVD+R and DVD-RW are the weakest links imo. DVD+RW can be overwritten instead of erased then written unlike DVD-RW. plus they r faster. DVD-R costs less and works better than DVD+R.
so like i said:
for write once media: DVD-R
for rewritable: DVD+RW