I was also interested in both and ended up with the SS only because I got a good deal. Somethimes I tend to over analyze and wear myself out in the process. All research indicates they are both good units. However, the SS upgrade is reasonably priced at $800 vs $2500 fpr the proceed. Additionally, the bass management is very flexible. You can have different settings for each input which is good. So I can boost the bass for movies and have the correct level for music. The major drawback with the SS is you need the remote in oder to set it up. On the other side, once its setup you can operate with or with out the remote. Sound quality is improved over my Marantz AV550 but still suffers because of my imperfect room. That will be my next project.
Good luck.