In reply to BenPitt:
I bought one recently and have used it for one indoor session only, and an hour of practice on my garage wall for abseiling. I agree with the previous comments about 'ok when you get the hang of it' for top rope and lead belaying, and the auto-block works well for belaying and abseiling. However, I am slightly disappointed about several things:
1) The inability to use a 'normal size' biner in the 'lever' hole. The control for lowering is better by this method than using the thumb loop, but I'd probably have to carry a suitable 'hook' to use in the hole, or buy an extra thin biner.
2) My (new) biner that I bought with it (DMM Sentinel KL HMS) now has two palpable grooves in the top surface - the points of contact of the Mega Jul with the biner are too thin and feel quite sharp. This much wear after just a few hours use is not good, and heavier use would presumably eventually make a deep groove and compromise the strength of the krab? I have gone back (as suggested) to an older but thicker biner.
3) At one point the wire loop (which as stated, is quite flexible) distorted enough to become partly trapped on the outer side of the biner, while lowering (maybe I was just incompetent) and this obviously stopped the auto-block working efficiently. A stiffer wire would be better.
Overall I think the basic design is good, but feel that Edelrid got carried away with weight saving (and indeed, it is a much smaller and neater bit of kit than the Mammut Smart Alpine, for double ropes) and thus compromised its strength and its compatibility with 'normal' karabiners. It could be beefed up a bit to stop the surface wear on the biner, enlarge the lever hole, and strengthen the wire - the extra weight would surely be negligible given the average trad gear carried on most climbs?