I wondered the same thing about the SPS difference and also the Contrast Ratio. Seems like the newer models are taking steps backwards. Perhaps the way they rate these features has changed. However, I did notice that the new 3D models have the 240 Hz, but Contrast Ratio is still lower. At any rate, I recently purchased the older XVT553. They may have stopped production of this model since I found it difficult to find new models. I also noticed that the owner's manual only mentions 120 Hz even though it says 240 Hz on the front of the set.
I have the set connected to the internet via wireless router. Now, if I could just figure out how to get to a music website I subscribe to. Guess I would need a browser window somehow.