Patrick Mulligan wrote a review of Edelrid Mega Jul Belay Kit on June 24, 2014
Familiarity: I've put it through the wringer
I actually do not have the steel biner sold as part of this set. However, I have spent over a year using the Jul and really like it. I still use a GriGri when sport climbing or cragging. With today's smaller diameter ropes (using mostly 9.5 or less these days) and with doubles this thing can't be beat. Its light, strong, and locks consistently with these ropes. It does take some getting used to, but once accustomed to the device its amazing. I will say that it is necessary (and recommended by Edelrid) to use the device "backwards" as a normal tuber when rappelling. It is a PIA to use it in locked mode, even with the biner as a lever. That said, I back it up in the same way I would with an ATC or the like when rappelling with an autoblock.
I will also say that it takes a little more effort than an ATC or similar for belaying the second in guide mode, but it has not caused me any issues.