The ki84 if flown correctly will more than meet the challenge.
I am finding this to be true. My main ride is the Ki-84. Before, I wasn't sure what I was able to do with this plane until I got to the 3rd tour of flying it. I am by no means a "great stick" in it, but I can hold my own most of the time. This is a great plane once you get used to it and learn it's perks and quirks. I have noticed lately that there are a few sticks that are cautious once I engage them. These are the guys that assess the situation or capability of myself I think. After flying this plane awhile, I fear no plane...just the pilot. I have the most difficult time with Temp/Typh's/F4U, and Hurri's. They know I can't dive without shedding parts and I am not a speed demon. I am pretty much a weekend warrior, so my score is never impressive. However, the last 3 tours I have racked up a number of kills with the Ki-84, whereas the other planes I don't achieve that much.
I have shot down Spits, La's, Yaks and Pony's, etc. But only when I can get them low and slow. If the speed bumps up and the fight is a little more horizontal, I usually don't survive too long. However, the planes I mentioned above like the Typh and F4U that have good pilots will fly circles around me, just don't let me catch you low and slow or at least slow... that will increase my chances of getting you.
On another note: the other plane/pilot I will be concerned about is another Ki-84. In the last 3 tours I didn't kill one. As a matter of fact, I was only able to bag one Ki-67. N1K's can be a challenge, but do'able. I do not (or try not) to engage bombers. I lose that fight most of the time. Ki-84's are not I would consider "bomber killers". So, bombers (B17, Lanc's, B-26, B24's) need to be approached with caution.
I also agree that the word "fear" is the wrong term. "Concerned" is a good word, but I like "wary" or "cautious" or even "leery". But not fear.