I haven't done extensive testing of the burn quality of my PX-760A yet, but I can tell you what I have found so far.
At 6x CLV there seems to be no relinking spikes (seen in LiteOn scanning drive).
At 8x P-CAV ther are re-linking spikes sometimes but more often there are none.
At 12x P-CAV and faster there are relinking spikes.
My external enclosure cannot burn at 16x and 18x with my setup without buffer uner-runs, and the buffer under-run protection in my PX-760 isn't very good at all - the quality really suffers when this happens a lot at the end of a DVD.
It's no surprise that the Plextor PX-760 (identical to the 755 in most ways) is very good with Taiyo Yuden media, and I've tried YUDEN000 T02 and TY CD-R media so far with excellent results.
Since I mostly burn at 8x anyway, I'm not overly disappointed about the spiking problem, and the relinking spikes don't cause the same type of problem as relinking spikes made by my NEC ND-4551A or Optiarc AD-7173A drives.
The relinking spikes made by my PX-760A are only apparent in LiteOn scans and sometimes as a small "blip" on a Transfer Rate Test in the LiteOn (165P6S).