Ian, The Ullman seats are padded but quite firm. Not sure what's under the open weave stretch fabric seat covers. Mine (like most Ullmans) are the jockey seats which need to hold their shape - Ullman regular type seats may be different.
All things are relative but the luxury comes from them taking the impact through the suspension rather than from the softness of the seat itself. You also need to sit back into them as I know of someone who did hurt themselves by perching in the front of the seat which is relatively unsprung. Greg Marsden is demonstrating them at 2012 Marine and is also doing the Round Britain Race.
We have fitted toe straps which I would judge as essential as the seats have no side support for good ergonomic reasons - you just need to keep a firm footing!