Saddle query from an old-timer

A pivotal seat has a bolt through the centre, accessible through a rubber patch in the top of the seat. This bolt threads directly into the top of the post. The seat has teeth on the bottom that engage on teeth on the top of the post, there's enough room and teeth to be able to change the angle of the seat. I'm sure a Google image search of a pivotal seat and sort will make that description a bit clearer!
They work really well, I've never had a problem with them, just make sure you've got a fairly long 6mm Allen key so you can tighten the bolt. I've never thought about comfort when buying a seat so I can't really give a recommendation, but as you say the angle is probably the main issue with your current one

Cheers Steve. Since posting this, I had a google image search and you're right, that makes it all make sense. Certainly looks like a simpler design that the old seat mounting bracket things I'm used to (http://i.stack.imgur.com/hheRl.png).

I had a look on chain reaction cycles and for about £20 I can get a post and chunky looking seat, so I'll probably go for something like that.

Check out the Tree Bicycle Co. Ergo seat. They make slim and fat versions. As you said, we don't sit much while riding, but when you do it doesn't get more comfortable than a Tree. I've tried several different seats and I always come back to them.

Thanks TKeck. Will check them out.

Yep! Tree Ergo seat is THEE most comfy bmx seat out right now.