AGentleStar: IIRC, the HitBox X Offset fix I suggested fixes sliding Up-Smash pretty well.
It catches foes better and links to the second kick more consistently.
With that tweak, Falcon shouldn't need any change to his initial Dash speed.
Falcon does not want to give up any speed.
I've decided I don't like reverse Knee, either. I prefer Knee to always launch forward.
I do like B-Reversible Falcon Kick, though.
AFAIK, mashing B to get Boost Power will no longer be a thing in 4.2 -- it will be "Hold B" instead -- but unfortunately, that awful 4.1 charge animation (and the unnecessary sped-up Up-Taunt at the end) will remain, and the charge will take longer to complete than it did in 4.0BC (which was the perfect length IMO).
BPF all the way.