I have...
Well sort of
Not as high as 12k yet, but 6 - 8k in OAT of 25, the Raven II performs very well. This August we had OAT of 30 and we found it to have loads more power at all levels.
Starting the engine in -15 was easy back in the Winter and the same in the Summer with 30 degree's.
It out performs the standard Raven in every respect so far.
Hope that helps, feel free to P.M me if you need more information
Happy