Another consideration might be the concealed draw that BBI teaches. It would be difficult to make it look like you're reaching for your wallet or to conceal your draw behind an object from appendix.
On the other hand, a behind the hip draw *looks* like a traditional draw stroke like people are uses to. At least what I think of all the way back to cowboy shows when I was a kid. So for most people an appendix draw may look less like a draw stroke. Or... Maybe a hardened criminal sees the appendix position the same way because that's how criminals carry? Maybe not? Just some thoughts.
The question is a simple one. Is it the faster way to go? Is it better?
That fact that many disparage the appendix position makes me think that there might be something advantageous there.
Faster and better are not always the same thing. So I'll answer separately.
Speed?
This is hard to measure without bias and also hard to eliminate other variables. If you take the same shooter who has been using the same method for some period of time and make them switch, they are likely to be faster using the method with which they have more practice (at least for some not-insignificant adjustment period). Comparing two different shooters introduces all new variables. Specific holsters, hand start positions, concealment methods, and even body type matter too.
I think when you compare the draw stroke paths, there are some efficiencies provided by appendix and some by a 3 o'clock position. From around 3 o'clock with a little drop on the holster, disregarding concealment, and starting with hands rested at the sides, the wrist or forearm is resting right over the gun. Just in front of the hip, forward of 3:00 is probably the most efficient in this way. This puts the gun directly in the natural path of the arm and can be faster, especially if the shooter uses a snatching motion to gather the initial grip on the way up (vs a more positive driving downward motion to secure the grip, necessitating a change in hand direction). The appendix position, on the other hand, places the gun directly underneath the eye. So the path of the hand to the gun may be longer, but the path from established grip to having the gun in the field of view under the dominant eye is shorter. The ability to efficiently pick up the sights in the cone of vision and drive them to target is where the most speed is gained in the draw (disregarding concealment), at least for me. Which one wins? Depends on where the hands start I think.
Then we have to add in concealment. There are a lot of variables here, but I'll assume a lifting method for clearing concealment for each because it works with both open and closed garmets. Appendix provides the advantage of keeping the arms/hands in front of the body where they are generally more dexterous and reliable. The amount of movement from each hand needed to clear the pistol and establish grip seems to be reduced from appendix. The off hand can generally be used to lift the clothing while the dominant hand moves to grip simultaneously. With a 3:00 and back carry position, the shooting hand is usually going to get involved with clearing the concealment, adding a step before grip is established. This is not always the case, as some shooters can clear strong-side concealment with the off hand. Even for them the path of the off hand is longer and less reliable. I think Appendix wins in speed from concealment for this reason.
Burl asked for draw times so I will add some comparison between a friend and myself. I carry on my strong side at 3:00. Jason carries appendix. If I use a reference time period where we both had a very similar amount of practice time, training, and similar overall skill level, I can compare draw times to first shot and get as close to apples-to-apples as I will probably find. During the reference time period I'd say a 1.75 sec draw from concealment in to a 4" circle at 5-7yd was a good average for me. I'd ocassionally push down below 1.5 and sometimes be closer to 2.0 sec. Jason, on the other hand, would average 1.5 sec, 1.0 on the fast side and 1.75 on the slow side. This is with a very similar level of practice and overall proficiency in most shooting areas during refrence time period. In the same time period, if you'd started Jason from a strong side holster position, his times would increase to look like mine. So I think there is roughly a 0.25 sec difference in speed from one method to the other based on those observations.
Holster types, hand start position, concealment, and experience with the draw all matter when we are talking fractions of a second. So giving a definitive answer is difficult.
I'll post separately about "better" and talk about the grapple that Vigilant mentioned. That is a whole can of worms on its own.