It is a lot. Do it as a bow and use it to shoot the boot - it will shoot it across the room, i bet.
This also gives you the idea: it's like any bow where you press the arrow (boot and leg) into the spring. Release it by flexing your leg (or other physics-mandated ways of reducing the centri-force, like angles, upper body or speed). It will shoot the arrow (boot+leg) to whatever extent - this is the float.
Well ok...I gather you can see the release is timed...not instant. Its not like letting a bow and arrow go "snap"...its like letting it just relaxing your arm but still holding the string!...the arrow wont fly far, if at all.
So now..."how much energy".
Flex the ski say 4 inches. I can push that pretty easily with 1 hand...even on my stiffest skis. Now, in transition, I can generate enough "rebound" to physically lift my entire body off the ground.....
Since the only energy the ski has, is what I put into it....and what I can put in, can be put in with 1 hand....that must mean that with one hand I can push myself up enough to launch my body in the air....yet I know I cant do that....so there must be something else going on.
Think of it this way....deflect a coil spring from a ball point pen say 1/4 inch...now add more pressure to collapse it fully.....now add another 10lbs of pressure....have you added more energy to the spring? No...because nothing has moved....the table is now supporting that extra 10lbs...and since the table is not elastic...no energy is stored, or returned. Same with the ski...the only energy it stores, is what it needs to deform...the additional pressure is supported by the snow....