Never seen them but doesn't seem like a bad idea.
I've never seen those either James but they do look kinda slick. My son sure could have used those one time last year when he came up short! It would be worth trying those out. Can you get the manufacturer to send you a set in exchange for a favourable write-up?
I wonder how this will work with the kick starter lever, will you not be able to do a full kick?
They look kind of cheesy to me and could possibly cause issues if you get you foot tucked back behind the peg which can happen. Also, this dude should worry about changing the front sprocket, before he tosses a chain grenades his cases...