I just went through the exact same scenario. RR S/C was way too expensive, and the RRS S/C is being marked up ridiculous amounts b/c they are new and hard to come by. They look good, but are still pretty slow even with the S/C. I find it hard to believe that the HSE would feel as quick as the 4.4, and if you look at performance #s, it is definitely not close.
I looked at the Cayenne, but it seemed overpriced. The used 4.8is was the choice for me. I just got it less than a month ago and it is an incredible truck, although the ride is a bit rough.