After reading all these posts and looking at a couple of other blogs Aprillia, rotax, Denso. I've come to the opinion...I stess opinion..that ambient engine heat, exhaust headers, skid plates etc have no effect on this failure.
The Aprillia fix seems to be a second ground on the regulator...implying if the regulator ground degraded it cause the stator to over heat.
Some stator failures show only a few coils are over heated, other show the whole stator over heated.
All this seems to indicate an age related failure of the charging system which manifests itself as stator failure.
Sure wish BMW/Rotax/Denso would speak up on this and put the speculation and all the wasted effort to a end.