Drawing from the appendix position is faster, uses smaller movements, and requires less overall movement. These things all add to its suitability in tight quarters.
That's absolutely false. When combined with the improved speed of an AIWB draw, the ability to have your hands practically on top of the gun in a normal relaxed position (as opposed to reaching/sweeping behind your hip) makes for a very stealthy draw... and one that doesn't rely on the BG demanding your wallet before you can begin.- If a close threat has already presented itself, an AIWB draw has effectively zero chance of being performed surreptitiously.
I think this is too situational to call an advantage or disadvantage for any given system. Hopefully Southnarc can chime in on this issue when he gets a chance...- In a ground-fighting situation, the argument has been made that AIWB prevents the gun from being trapped between your body and the ground. While true, it creates the new problem of trapping it between your body and your opponent's. I haven't tested it, but it seems it would be easier to raise/rock yourself far enough to clear a belt holster than to get your hand between two bodies. Once you had a grip, I think it would be easier to draw from a non-AIWB, and the resulting "start position" of the gun would be more advantageous.