Most recent update..........
Worst case scenario (2X 6701/6702) still shows a net gain using the -advmethods compared to both non-advmethods on the 450, and my previous PPD on the same setup using the GTX275. SMP2 6701 PPD is around 8.5K vice the aprox. 10.5K PPD running GPU2 with the 275. Combined PPD over all clients in this situation is sitting around 38.5K PPD vice the 34 - 36.5K I was seeing with the GTX 275 installed.
Definitely an improvement over the 275 while using -advmethods, but I suspect that's only with a single GPU client running, and that the hit to CPU cycles would dramatically decrease PPD on time based CPU clients/WUs (such as SMP2 or Bigadv).
Temps with the -advmethods WUs are still amazing even though I've dropped the fan speed down to 80%