Frodo's seat are very comfy and adjustable, but they are simply too thick! The depth of the seat base and the sliders means that my eye level is slightly above the top edge of the windscreen! This leads to either, a very uncomfortable slouch while driving, or only being able to see the road 15 yards in front. Actually, this is more view than you really need in a commer anyway!!!
I am looking for something with a shallow base that's adjustable, but it's right down my list of priorities atm.