Actually, the roll rate was slightly reduced. It will still out roll many planes in the game (including spitfire). It's NON-wep engine boost was increased 50% (from 200mm to 300mm) and it's WEP boost is double that of UN-wep (400 or 450mm, can't remember).
It got WAY too much power. I liked the non-wep version because it had these skills but it also had limitations.
Now I see the ki84 as another late war uberplane. I fly it once in a while. Still use it to kill P38s. But just not as fun, now that it's that much more powerful it's just too easy.
Going back to our current P38: Yeah I'd say it's uber. At least in the neighborhood. It has nothing to fear most of the time. It can zoom better than any plane in the game. Better than a G10. Better than an f4u4 (I've fought some recently, I can attest to this). As well as a ki84. All it has to do is pull up over any target, let that target stall and fall down on it. If the target doesn't then it comes down in a perfect place to saddle up (what with having no torque to roll it)
Coupled with the ... uh... "current state of USAAF flaps"... this plane definitely falls into the "uber" class for me.
I just hope the others fly WORSE than it. Might make me fly it more.