i've got the half-thick full-size black one, and also the standard dressage pad, to use with thin saddle pads. i use that a lot more than the numnah tbh. will use the numnah for early breaking work though.
I use the Prolite pad and its fine but bought the all in one Prolite numnah and can't get on with it. It could be because its a bit small for my saddle as it keeps slipping.