For some background info, I've been climbing and belaying top rope for about 2 years, at the moment, I'm practicing lead belaying and prefer the ATC over the grigri when I belay because of the least friction when taking and giving slack.
I've researched the giga jul and mammut smart 2.0 but see too many cons from the community from those two.
I would like to use the giga jul because of the versatility, however on thicker ropes, many people report issues, seeing as how I will do a lot of belaying with indoor gym ropes, this is a serious disadvantage, but the advantage that it has for multipitching and abseiling sounds amazing.
I would need this belay to be auto locking because of gym rules.
I watched a video discussing confusing the handle loop with the rope loop with the giga jul but they mostly said how it could be confused visibly and that painting it a different color could help. I will keep this in mind. Is this why you stopped using the mega jul? Because the versatility of the giga jul seems pretty attractive. I also have an edelrid bulletproof and so I like how solid edelrid makes their equipment