I'm going to kindly push back a little on this. I think forward pump and pendulum is much easier form for amateurs, allowing one to abandon arm to gravity and enabling one to feel weight of disc better than static disc with still arms. You can still, at least somewhat, work body around disc.
I've never experienced what you're talking about, but I have serious doubts the gains can outweigh the likelihood of rounding and swooping.
You can still totally work your body around the disc; as was stated, a lot of top pros do. It's just not as obvious or forced using a pendulum.