I promise I won't beat a dead horse here :)
The Green drives use "Intelipower" technology to adjust RPM as needed, so the drive doesn't spin at speeds unnecessary to the task. That's why while I'm editing off of them, they perform at full speed (forgive me I don't actually know the max RPM) and then spin down when not needed. As I say, we use them all the time, and I trust their reliability, but that's me. I do have a couple of Black drives, and my experience with editing off of them is that because they run at a much higher RPM whenever they're in use, they get quite hot. I did a 5 hour render of a feature length film on a Black drive and it was uncomfortably hot to touch by the time it finished. I haven't noticed any speed differences using the Green drives, that is to say that they perform just as well as far as I can tell with read/write times. I do long renders on them too, but they do stay a lot cooler and as I say I haven't found any reliability issues whatsoever.
As far as the Red drives go, I have no personal experience with them, I've always heard that they're somehow optimized for NAS use, so I just stuck with Green and Black drives.
I'd say if you can afford it and want the absolute best performance, absolutely go with the Black. However, if price point is indeed a worry, I wouldn't dismiss the Green drives due to the fact that they are "low power" because they are indeed reliable for video editing.