v5 and up can typically read +R OK, but there have been some v5's that had issues with it. I think I recall some posts that some v4's were reading +R from time to time. This is a really old debate, and really a mute point these days unless you have an older PS2. If you've got a newer PS2 (last 3 years), you should be OK--give it a shot!.
On my v5 the +R's seemed to have a slightly better load time with some games. I have noticed that it doesn't like cheap +R media though, and even the good discs needed to be burned at either 4/8x--in contrast I've burned -R's up to 12X and they load just fine. It's also not so picky about the brand on the -R media--even el cheapo Princo's run on it just fine.
If it ain't broke don't try to fix it! But, hell if you can tweak that bastard just a little bit more....hehehe.