Quite some time ago, I managed to test out a 68x Star Data CD-ROM drives, at the computer store I use to work at. They preformed extremely poorly, and had a lot of trouble reading certain Cdr's and were very loud. Since we stocked them for quite some time due to the fact that the pricing were cheaper then most CD-ROM drives, we started to receive many faulty ones coming back with unhappy customers which wasn’t much of a surprise.
I usually try to avoid generic branded high speed CD-ROM drives but you never really know until you try them. I once saw a retail package claiming that it reaches speeds to a 100x. with a 100x stamped on the front of the drive. I wander how well they did, since I never saw it being sold since that sighting at the swap meet (computer market)