In reply to PPP: Personally, I thought the design was a superb idea when I saw it.
My immediate thoughts are that the Edelrid 'slider' design (and for that matter the new Grivel one) could be great for when belaying with an Italian hitch or for when clove-hitching to anchors. Both of these are scenarios where it is hard to do so quickly or one-handed with standard autolock designs. Also, depending on the risk of rope abrasion against the slider mechanism, the offset D version might be really good as the blocking krab for guideplates.
Anyway, I'm extremely keen to play with one the first time I end up in a shop that stocks them. By coincidence, I was ordering gear online earlier today and I thought seriously about buying one but in the end the price and the fact I've not handled one put me off.