Let's now go back 20 years when small of the back holsters were all the rage. Same rules apply. Has drawbacks, hides well, etc. It's no longer an accepted method by the masses due to inherent flaws. The biggest being that the person behind you can easily stop a draw and falling on your back can cause a broken spine.
My biggest issue with appendix carry is when I'm seated. I don't generally mingle with the public in an unknown venue very often, but when I do it's usually in a seated position at a conference, class, restaurant, or movie. It seems that a different method of carry would better benefit me. I'm currently testing out a new hybrid style holster called the Berkut II by Green Force Tactical/Forward Training Concepts. It's an improvement on the appendix by changing the draw stroke slightly and in doing so, making it slightly more sit friendly.
Another issue that seems to be at the forefront is pistol ammo. Everyone wants the new hot ticket. They change carry ammo more often than underwear. That (in my opinion) wasted ammo money would be better spent on FMJ at the range. Super performance ammo isn't worth a dime if you can't get solid hits. Even worse, misses with this ultra performance voodoo slug could be more harmful to an innocent if you hit them. Stick with the fundamentals and do your work at the range, not on the keyboard, unless of course you are testing your new wiz-bang holster by typing in a seated position.
BTW, not sure I'm going to stick with the threaded barrel in this configuration. It's protrusion happens to make contact with my personal protrusion, and that is an unwelcome distraction.