I'm running 6Ah 4S packs and am getting about 20 minutes of runtime in a track environment. As for comparing it to the 6XL, I think it's better. The 6XL, in my opinion, would be too hot for a buggy on 4S lipo. With the 7XL NOTHING runs hot. Everything is as I envisioned it would be for the track. I can run pack after pack and not worry about anything, except the occassional broken part.

As for the speed, I don't know. I set the buggy up to run on a track. It just so happens to be the fastest thing I've seen at our track. I did get it up to around 50 a couple of times when I was messing around in a parking lot with the gearing, but that's just stupid fast for an 1/8 scale buggy. The suspension just wasn't set up for it. If you're looking for speed, a buggy is not the way to go. Not without modification anyway.