I'm not sure what the truth is about the performance of the Ki-100. I think the combat account versus the U.S. Navy is now accepted as unreliable (although a fight at that stage of the war says less about the actual aircraft). I think therefore the report of the Akeno Army Flying School instructors regarding the comparison with the Ki-84 must also be treated with scepticism.
There was already a post requesting the Ki-100 to be added here:-
http://bbs.hitechcreations.com/smf/index.php/topic,164462.0.htmlHard to see how it wouldn't be an improvement in terms of handling over the Ki-61 given more power and less weight, with essentially the same airframe.
Interesting aircraft regardless, about the same size as the Bf109G-2 that was there. Both looked tiny in the shadow of that Mosquito!