YPC,
My MT-4 transmitter w/RX-462 receiver has telemetry that returns the main battery voltage for Cell #1 of the Nano-Tech 6S LiPo battery that I use in my model. I also monitor the temperature of the motor.
It's very interesting to watch, in real time, the effect of throttle use on the battery voltage. For sure, the more you use the "Juice", the quicker the battery voltage drains. Also interesting is watching the battery voltage recover a little while I sit in the lineup waiting for a set. As the battery gets near 3.7v, which is the point at which I bring my model in, the telemetry shows the cell value fluctuating around much more that when the battery is near full. My runtimes are pretty good at 40 minutes+ under normal conditions and up to as much as 60 minutes when the waves are inconsistent. As for water temp, our water temp here in SC is almost always in the 60's. My motor temp shows between 70F/85F under normal surfing conditions. There have been several times where the temp has shot up to 120F..... yup, the cooling lines do get clogged with sand or seaweed sometimes. I just bring him in, blow out the lines and chuck him back into the lineup.... heat in the compartment is not a good thing.
What has been the effect of your settings tinkering on runtimes?