What kind of shape are the originals in that you are trying to copy. I've used my plextor, (not bought from MTU), and just about every brand of CDR media you can think of with Chartbuster stuff, and almost never had a problem copying. I wonder if this can be a current drivers issue or something? As for the speed of the burn, I've typincally found that the new plextors write better the faster they burn. If your disc are brand new, not filled with scratches there may be another issue.
There is also a product called a "Disc Doctor" that will do a great job of repairing the playing surface of a scratched disc. If used it on disc that would even play anymore, and restored them to perfect playing condition. Just some things to think about. Also remember that what plays good or OK on a regular CDG player, may not play as nicely on your computer.
