Mine did 14x with a clean pressed disk after the speed hack. With burned DL it was slow, with minus it has a drop about 1/4 in then picks right back up to finish at 16x usually. I think I'd like to pick up a AOpen 1648 soon too, sounds like a good fast drive.
Maybe I'll try the biggest pressed DL I have and see if it hits 16x but the speed hack isn't perfect with burned media, seems OK with pressed disks. Doesn't seem to affect the error reporting at all though so people can try it and see how it does for them.