I have two TLR1's, one for the G17 and one for the G19. After several hundred rounds, the lens gets pretty clouded from powder but it doesn't really affect function in low light situations.
TLR-1's here.... Supposedly the Surefires hold up better but the only problem I've ever had with the Streamlights is getting them real super wet (pay attention to the seal on the battery compartment, and don't knick it up).