The reason I wanted the 6L at first, was because it is about 4100KV which is way lower than the CC 4600 motor which I originally wanted to run, but decided against doing it. I though this motor would run a lot more efficiently than the CC motor and give me more power... I think I'll go with the 7L motor though. 3500KV on 3s sounds just about perfect, and then i can gear up or down depending on temps, and speeds/run times.
I'll wait for a few more people's opinions, and then I'll make my final decision.