Just got one for my TT bike, it seems more comfortable and avoids the numb nuts effect which was getting a bit worrying. They take a bit of setting up to get the right position and there was a bit of trial and error involved. I thought it was set up right on the turbo but then went and did a ten and it was all wrong. This was echoed by a club mate who also has one.
Feels a bit unusual but seems to work – not cheap though, I bought mine from the states, added on c£18 for VAT and clearance charge. So overall so far I like it, my clubmate say’s he would never go back to a normal saddle for tt’ing
This may be of interest;
http://www.timetriallingforum.co.uk/index.php?showtopic=56599&hl=adamo