I hit with both, though not at the same time. I didn't like the S at first, but by the end of my demo period, I really liked it, especially the power on deep shots (approach or from the baseline). The non-S is ok, but I had more trouble with maneuverability, which is weird because it is supposed to have a lower swingweight than the S. When I was prepared, ground strokes were awesome, but volleys just ok - volleys with the S were mostly good (read: better). The S was strung with 4G and the non-S was strung with Sensation 16, and I am die hard fan of 17g string. So, I don't know if a 17 would give me better results for the non-S or not.
One interesting note: I hit with the 105 S version and it had some WICKED power, strung with 4G in the mains and Gut in the crosses (in fact, my friend is selling me his 105) and when I picked up the non-S version, I was hitting almost all short balls. I partially blame this on being a little tired, but it was interesting all the same.