[lincpimp]

I would stick with the 8xl, it will run cooler and be easier on the lipos you have. The 7xl needs a really good battery to perform at its best. I have a few that I run with trakpower lipos, and they work fine. The maxamps 5k and 6k packs I had did not do as well as the trakpower. Plus the 7xl is more gearing sensitive than the 8xl.