When comparing Climbing Technology Alpine Up vs Edelrid Mega Jul, the Slant community recommends Climbing Technology Alpine Up for most people. In the question“What are the best belay devices for rock climbing?” Climbing Technology Alpine Up is ranked 7th while Edelrid Mega Jul is ranked 12th.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Auto-locks even if brake end of rope is not held
In case belayer is disabled, etc.
Pro Lightweight
Pro Passive assisted braking
Pro Three rappelling modes
Can be used in 2 orientations, for rappelling with or without brake assist, and can add a carabiner for lever action, making it similar to a GriGri.
Cons
Con Behavior is highly dependent on rope diameter and type
"stiff ropes feed very poorly. 9.7 and above ropes feed poorly for lead belay. Soft and supple skinny ropes don't lock as abruptly. Half ropes in the 8-8.5 range DO NOT LOCK FULLY with the proper edelrid strike biner" https://www.reddit.com/r/climbing/comments/6aoipn/nonjerky_method_for_rapping_with_mega_jul_in/dhh1vvx/
Con Guide mode with thin ropes can flip and disable auto-blocking
Video demonstration with stories of it happening in the comments: https://www.youtube.com/watch?v=385cP_FYNEs