I have the SPis and I have the say, the response is money. The foot beds are great and the ankle strap is comfy.
My only complaint is the weight is a tad heavier due to the aluminum, but it doesn't seem to matter... I can get more pop out of the board with the SPis.
I was bitching about the ratchets not releasing when I first got them, but am now getting used to the way they work.
I agree with the others though - too stiff for the park.