Here is a section of another graph, but with 4s and everything else the same. I had another plastic spur and decided to use tighter gear mesh this time. I Forgot to mention that the ambient temperature was about 45F for both runs.
Gearing: 12/46
Battery: NeuEnergy 30c 4100mAh 4s.
Timing: 0
LVC: 13.0 volts
Punch Control: 60%
The pack was not fully charged, but I managed to get 2500 mAh out of in about 8 minutes of running or about 18.75 amps on average. Same as with 5s, although i was on full throttle much more of the time. You can see in this graph that it takes about 25 amps @ 14v or about 350 watts to maintain a speed of 40mph.
Also during the run:
Max current: 94 amps
Max speed: At least 42 mph
Min Voltage: 12.09 volts (something is wrong

and this has happened before and on the graph near the end of the run there is a sustained voltage of 12.4 volts!)
At the 5 min mark, motor temps were around 140F. At the end of the 8 minutes temps were 148F on the motor and 110F on the battery.
One other note: On both graphs when rpm is decreasing and current reaches 0, after that is actually current being put back into the battery.
Anyway, it's pretty safe to conclude that this motor can handle 5s just as well as 4s and ideally you would gear lower with 5s. Yesterday, although i didn't have any measuring devices, I did another 5s run in a wide open area, with full throttle most of the time and I could keep my hand on the motor for quite a long time without pain.