I think you are right: "When you get close to the ground, the downdraft will stop, though spitting you out the bottom is still a risk."
I think due to dissipating of downdraft near the ground created all the problems: sinking, ballooning and floating. I should've reduce some power little early before my aiming point. I think it would help a lot! Now I can't wait to test for it! ( still, I prefer to fly in a smooth and calm weather!
)