i can't believe the "green laser" debate is still going. lol. It was very interesting seeing those couple of shots with green lasers from the early trailer though, but i don't think they ever actually intended to go with the green lasers. Sometimes when trying to get a trailer ready in time they go with unfinished FX (which is clearly evident in early trailers). A lot of the lightsabers haven't even been rotoscoped in the trailers, so it could just have been an error of the FX department, or just test FX that were used.

While the green lasers would make more sense and help distinguish between the rebels laserfire, red just looks more powerful than green.