Snowboard boots with flexibility

[Matt V]

I am looking to pick up a 3rd pair of snowboard boots for snowkiting.

I currently own 2 pairs of "Head" boots that I think were a cheap Chinese rip-offs. But I love them because they flex the most out of any boot I have ever used. Too bad they are at the end of their life.

I also picked up a pair of Burton "Invader" boots on Craigs list that are almost flexy enough to use for snowkiting. But I prefer not to use them if I can avoid it. They just work my legs way too much. By the way - their flex rating is "2" or nearly the most flexible you can get in Burtons.

I also own a pair of Burton "Moto" boots that I use on the hill. These boots are stiff enough and have so much forward lean to them that I just plain cannot use them to snowkite with. My legs are fried in 15minutes with these boots.

Any one have any other favorite brands/models for flexibility? Sizing recommendations would be nice too.