Well, I called InFocus twice. Once to their CS department and once to their technical department. Ironically, the CS department gave me the most technical answer.
The CS rep said that since the contrast ratio on the TDP-S2 is 400:1 it has to be the LP340V. The LP340B has a 500:1 contrast ratio. The TDP-S2 also has a DVI port unlike the 340B.