ORIGINAL: Richard L.
Really, all the S&S versions have the 10 proportional speeds? All of the cheap S&S versions I've seen on eBay were advertised as having only 2 speeds.
Then they're mis-selling them. The S+S tanks use different electronics to the non S+S. The non S+S tanks have a 3way switch to change the frequency the S+S tanks use crystals.
If you look at the bottom right of the controller and it has a switch then it's a non S+S but if theres a crystal then it's S+S.
Also the three switches in the middle are different.