I played with someone from this forum a couple weeks ago, I forgot who it was, and they were using the 51D in dogfight and did really well with it. In my experience with it, you gotta stay off the rudder or it will stall out badly and you gotta keep up the speed.

I'm going to try out the 109G-10 tonight. I used it in arcade when I played arcade and it did well. I haven't tried it in sim yet but have used the F-4, G-6, and K-4. The F is very manuverable and pretty good, but is weak in the guns. The G-6 is heavy and pretty much flies like a tank to me, but has great guns. The K-4 I like to fly. It is very stable, fast, and has great guns. But it is not the best turner. Every plane has a weakness.

A lot of planes act similiar in arcade as they do in sim, but everything is more exaggerated. The 51 stalls out in arcade too, but it just hangs there in the sky and doesn't respond for a few seconds, whereas in sim it goes into a spin. Same with lots of other planes. Fast planes (K-4, all the FW's, LA7) are fast in arcade as well. The Hurri might go 650, but faster planes go way off the scale and still easily outrun it.

The arcade in this game is still tons better than any other arcade I've played.
I don't think it's degrading to a pilot or reflects on his ability. Sim just takes practise that some pilots are unwilling to put in, for whatever reason.