Hey @JSampson , thanks SO much for this link and video. Never even bothered looking at the feet when i installed my kickr.
Pulled the box out of the garage and switched to the small/light feet. 
the increased lateral flex - though it took a bit to get used to it standing and sprinting.
I did see in the manual what you mentioned about the feet being classes by weight, but im 170#/77kg (
) and didn’t feel particularly unstable. Feel like im getting a little more balance and pedal stroke practice.