Hi Olli,
I think I completly agree with you here. I gave those two example because they are obvious symptoms that your MOT_THST_EXPO is a long way from correct and that it should be checked before moving forward. For most aircraft and pilots they do not operate over such a broad range.
It is worth keeping in mind here that ArduCopter has been designed to operate over a very broad range of aircraft and applications. As such we must me more comprehensive in our approach. This also means that many pilots can afford to ignore settings like MOT_THST_EXPO while others it becomes a critical variable.
I have often said “It is easy to make a multirotor hover, it is much harder to achieve the same level of confidence at the limits of the aircraft’s performance”. MOT_THST_EXPO is one of those settings that sets us apart from lesser autopilots.
So to directly address your question as I understand it. You are correct:
From what I have seen from T-Motor ESC’s they appear to do some thrust linearisation on the ESC and therefore aircraft using these ESC’s would be better off with values of 0.0 to 0.3.
Other than that, your average aircraft will not need to adjust MOT_THST_EXPO and it can be ignored as it has only a mild impact on the results of Autotune and most pilots couldn’t tell the difference anyway.
A little while I tuned a very small commercial vehicle using tiny brushed and geared motors. Thrust measurements lead to a negative value of MOT_THST_EXPO. This completly revolutionised the quality of performance and tune.
Another example was a large commercial aircraft using current controlled ESC’s. Again this needed a negative value of MOT_THST_EXPO.
So to summarise: If you have achieved performance you are satisfied with then you can probably ignore MOT_THST_EXPO. This will be the case with the majority of aircraft.