I have played both Allied and Axis, and let me tell you... both sides have planes capable of doing the job.
When I was Allied, the 51 and Tiffie had the speed, the Spits had the stealth.
The LW side has stealth and speed as well, not to mention outstanding climb.
What I see is this; lone-wolfing is tougher in the SEA. Twice last night I wound up low between two 51's in my 109. Handling one would have been easy enough in either case, but I got my ticket punched both times (after a good standoff) when they used their advantage (coupled with enemy ack). I wouldn't have had it any other way (ok, maybe away from the ack
).
Of course if you listen to Hangtime it was all a cakewalk for the Allied.