For a Jazz 80-6-18, I guess their car specific ESCs are an option. They don't have any HV ones though. :) Another idea I have is to try forward/reverse mode to see if the throttle responds the same as forward only. Will let ya know.

After thinking about it for a while, for dirt track racing the brake-to-speed behaviour might be advantageous. Kontronik must have had a reason to program it like that - maybe they know something we don't. :)

Temperature started at 80F, which is 26C which sounds right for today's ambient temperature. Summer here. :) I think these motors max out at 200F (magnet limit) so there is some headroom. I'll see how things go when I get my closed body and take it on the track. If it's still bad I might attach a heatsink that protrudes through the top of the body.

I think your Jazz will be version 8 too. I don't recall this behaviour from my version 7 Jazzes. Heck, if version 7 doesn't do this, we could ask Kontronik to downgrade our Jazzes. :) Only improvement I noticed in version 8 was that forward/reverse mode was made usable.