The Teflon rotors will have tighter tolerances making them more efficient then the bare. Only problem with Teflon is that if you are overdriving the supercharger esp. without some type of intercooler the rotors are actually going to expand because of the heat and blow off the Teflon and tear the supercharger housing up.
Don't know - Haven't been here long enough to know that they ever changed. If I had to guess. . . . Willwren was saying that a few members bought these FLOZ superchargers that were junk - Maybe DrJay and Willwren were the ones that bought them? Who Knows?!?! PM one of them if they don't chirp up.