I found the TREX450SE V2 download to be way more (over)responsive, twitchy and harder to control than the B400.
I even changed some of the settings like shortening the flybar, reducing the overall pitch and flybar deflection.
The results were not much better.

Now I'm flying using the TREX600 EA download.
It's all messed up on the ground, spins uncontrollably, but once you get to lift off speed it settles down.
I like it, but then again I liked the way the Impala 3D flew compared to the B400. Just a little too sluggish and heavy feeling.
So, I'm sticking to the TREX600...but that's just me.

Check out www.knifeedge.com and try some of the downloads.
You should be able to find something that you like.