Knee shot is such a good move imo. Mainly because it shortens your jump and you can keep a good momentum going in block strings (short hop KOF style lol). It also helps a great deal in Deejay’s vortex, making people second guess your crossup j.mk. Sometimes you can crossup with knee shot, but I have only been able to do that on crouchers. I have found good use of it too in safe jump scenarios. As an added bonus, you can make good use of it to get over projectiles as well, shortening your time in the air.
As far as being able to stuff things, it beats out everything you meet in the air for the most part, which will reset them creating another mixup opportunity. Like Tyram said above, during their reset period there is usually ample enough time to walk underneath them and start a combo on the other side (I try not to get too predictable with this as it is rather gimmicky). Other things Knee shot stuff from my personal experience would include Guile’s flash kick and Rufus’s Messiah kick (there is a certain timing for both). Has anyone else been able to stuff other reversals with it?
My favorite combos off of knee shot:
ks, c.lp/c.lk, c.lp, c.mk (sometimes it is just better to do 1 c.lp when you think c.mk will wiff.)
ks, c.lp, c.lp xx hp MGU (or EX MGU -> EX SK/dash ultra)
ks, c.lp, c.lp, c.mp xx hk SK