As lostone1413 pointed out, appendix carry is very fast, and much more accessible in wider variety of circumstances/positions than typical strong-side hip carry. A few top-notch trainers, including Gabe, are endorsing it recently. Gabe has a Changeling IWB on order with me, and a couple other trainers are using my Changeling to carry in this position, with full-size guns like Glock 22s and SW M&Ps. And one of my better customers carries his Commander this way, strong-side at about 1 o'clock, gun angled back so the grip is pointing down.
The original Summer Special was designed to be carried this way. That holster was designed by the late Bruce Nelson and licensed to Milt Sparks by Bruce. Bruce was an undercover narcotics officer, and there are photos of him carrying his Summer Special design in front appendix carry. The original Summer Special was a single belt-loop design, and the loop was slightly oversized for the belt. This allowed the holster to ride vertical when standing, but shifted and angled when seated.
All this said, I have tried it with several different sized pistols and I personally do not find it nearly as comfortable or concealable as strong-side hip carry; and this coming from someone who makes holsters, and has guys endorsing his holsters for this carry mode! I'm not that overweight or out of shape (5'11", 185 lbs) but if you have even the slightest gut it will push the grip/upper slide of the pistol out away from the body. I personally don't know how these guys are doing it. There are claims that it is more concealable than strong-side hip carry, but not for me and my mode of dress anyway. I can conceal a full-size 1911 under a banded-bottom polo shirt on my strong-side hip no problem. I cannot conceal a much smaller pistol under the same polo appendix carry. I think you need a heavy baggy sweatshirt or loose draping sweater, or photojournalist vest or jacket to conceal appendix. And carried up front under a jacket it is much easier to flash in a just of wind or with movement since it is right near the jacket opening. And yes, I find any pistol pointing at my thigh or family jewels a bit disconcerting even if I designed and made the rig it's in.
I've said this here before - Everything in concealment is a compromise. Almost without exception, the more concealable and hidden a gun is the less accessible it is it.
If speed is more crtical to you than comfort and concealment, appendix carry may be for you.
