Keep in mind, this is *not* the pure dogfighting version of the Ki-61, but rather a Jabo a/c. So its climb performance is worst than the 109E.
However, in a nose down attitude it can become a nice turner provided you dont dive in too fast. The twin HO-5 20mm is a VERY lethal package. Though the clip may seem a bit short, its because the guns fire so fast

A good clean decisive shot is all you really need.
If you can keep the engagements short, you can win with it. Once the fight becomes protracted and long, the inability to accellerate and lack of top speed (for a 1944 plane) will come back to bite you.