I bought one, you can log rpm after every run, see what max. temp your motor was at. Limit max amp to reduce heat generated, the full case is aluminum as well so cools efficently. I just don't like that you need to use their sensor cable as the plug which plugs into their esc is different.
I Bought second hand from UK about same price as a new sp. If you are buying brand new it is very expensive, maybe ask the 代理, I think it is the same one as hpi.