In reply to UKC Gear: I've been using the Gridlock for the past few months paired with a reverso 3 mostly multi pitching. Personally I never had much problem before with cross loading as I was using a Petzl OK Oval screwgate which didn't matter if it moved about as it tended to sit so the spine was loaded. The roundness of the Petzl OK Oval screwgate made it an ideal partner for the Petzl Reverso 3 in guide mode feeding smoothly and I like the quick red visual indicator as to whether the Petzl Oval is screwed up tight.
A few thoughts I've had about the gridlock.
It's a novel way to deal with keeping the screwgate orientated, though it's a bit faffy getting it onto and off of the belay loop on the harness. Once or twice I came close to dropping my belay plate off the Gridlock paying too much attention to the puzzle of extricating the Gridlock from my belay loop. However I've gotten used to this now and make sure to hold onto the belay plate when I'm fiddling the Gridlock on/off the harness loop. Not a big problem once you're aware of it and pay attention.
The Gridlock's rope surface at the top is fat and rounded and used with the Reverso 3 in guide mode is nice and smooth feeding. In guide mode I haven't noticed the Gridlock rotating so the rope sits on it's spine due to the shape which wouldn't be ideal as it probably wouldn't feed as smoothly.
The alloy the Gridlock is made from seems to be wearing faster where the rope runs than I've seen with other carabiners, though I have been climbing a great deal in the last few months using the Gridlock. There is still plenty of material left and though it won't need to retired any time soon I don't think it will be as hard wearing as some other carabiners out there.
Compared with the Petzl OK screwgate I was using before the Gridlock is 6g heavier. Whilst it eliminates cross loading I don't think this was ever much of an issue with the Petzl OK. The Gridlock is definitely a bit faffier than the Petzl OK but you soon get used to it. From wholly unscientific and not particularly rigorous testing I feel that the Gridlock wears a lot quicker than the Petzl OK. The Gridlock lacks one of the features I really like on the Petzl OK, the red indicator to show at a quick glance if the screwgate is done up.
I also have some concerns about misuse of the Gridlock, would be interesting to see some testing of the consequences were you to stupidly locate the belay loop in the larger separated area of the Gridlock rather than in the designated section and then load it.