I've had my hope seat clamp for about 3 years of hard use and cannot fault it. Definitely worth paying the extra - looks awesome and holds the seat very firmly without having to do it up so tight that the clamp becomes stiff. It's the part of my bike that never gets any maintenance, is always in the crud firing line and gets used at least four times on the average ride.
This product has two jobs: Adjust the seat height and hold the seat at a desired height. I find the lever requires very little force to be in a position where the seat won't move and so adjustability is easy to. Its a smooth action and you know its doing its job because you never need to think about it. Simple, but affective. Also there is an added bonus that it looks awesome.