I fell for this one a couple of months ago. Bought 200 of 'em, and wish to God I'd gotten a brain for Christmas, or else I'd have avoided them. To put it simply, they suck. The 8x can squeeze by at 6x with not a lot of trouble, but you still get a lot of bad burns, and you'll run into patches in the stack where a bunch are just fried out of the box. I run Pioneer and NEC drives, and always check compatibility first. These said on the specs they'd work perfectly with those drives. What a crock. Avoid these if you want to actually keep your data. Even if they pass verification, I promise you, you'll pull one of these out a month later, and you'll get CRC errors out the wazoo.
If you can find them, and you run Pioneer or NEC hardware, the newer 8x Optodiscs are absolutely friggin' awesome. Very impressed with those. Only trouble was with Shop4tech, because they sent me a pack of Optodiscs, and inside the spindles they were... --do you see this coming yet?--, the very same crap mentioned above. DVDInfo and DVD Identifier both say they're TYs, but if they are, they're rejects. My money says they're fakes, though. If you can get actual Optodiscs, they kick ass.