Yeah, I know, it gets bloody hot here too. Generally, I don't run on days where it's over 100. Hell, I don't even go outside!!
3S is going to be a BIG jump from 7-cell NiMh!!! Hope you have a good bumper on the thing and you've got some wide open space.
Shoot, you're in Texas! It's all ABOUT wide open space! So have fun!
