my experience is not too bad. two times we sent an esc in for 'service'.
it came back like new and it the cost was something like 50euro with shipping.
for my burned one i could buy a new one with 30% off. it was my fault the esc went up in smoke, because the tranny was nearly blocked because i made a mistake in the hurry i was fixing the center tranny it in the pit. full throttle with a hard tranny in the summer was too much. my guess is that many of the burned 18.97kw in those days, some years ago, were due to a too long gearing with the bigmaxximum (savages fixed in 2nd gear etc). by then we were not so experienced. by now motors with lower rpmv are used in the big trucks than the bigmaxxium. the big maxximum cannot be geared very long its too high rpmv. those who were driving the bigmaxx with the tranny locked in 1st gear never had heat issues. however i agree that they are not very 'nice' in e mail contacts there.
i see that castle for instance is very accomodating in replacing burned esc etc. however i guess in many cases the users can just be lucky because i am quite sure that many failures are due to a wrong handling of the esc. but who knows. i may be wrong.
however my target is to avoid warranty issues at all.

so actually i do not care that much about it.
bye
rhylsadar