I'm actually thinking about switching to an 8.5 or maybe even 9.5 now. When I was out there Sunday there wasn't a single section of the track where I was really able to use the 6.5. Heck I was getting 20 minutes out of a 4600mah shorty pack running at close to race pace. The motor was hot but I could leave my hand on it. I didn't even have the fan on my Tekin RSX and it was just warm.
On the one long straight you come off a table top so maybe 12 feet of the 80 are gone before you can get on the throttle. You can probably be on the gas for 50 feet or so before braking for a fairly tight 90 degree turn at the end.
I like the track and think it's fun but the 6.5 just seems like a waste out there. Most of the time I was only using the first third of the throttle. For the race this coming Sunday I'm going to dial in some throttle expo and see how that feels then decide if I want to change the motor.
My LHS created the track and sold me the 6.5 when I asked what motor to run. But that was before they knew much more than the overall dimensions of 50' X 80' so it's not really their fault.