I have been an AIWB convert for nearly 15 years. Started carrying appendix back when Gabe Suarez first started pushing it hard back at the beginning of the movement. Back then, there was a pretty large group of anti AIWB that made sure to let you know how idiotic you were any time you would share your carry setup, or suggest it as a valid carry option. Lots of references to mexican carry, etc.
Bought a Dale Fricke archangel holster as my first AIWB holster. At the time, Dale was one of the only people in the game making good AIWB holsters. His design still holds up. Still a favorite and carry with it often. That and a tier 1 concealment holster are my go to holsters.
Even way back then the benefit of fitting a reload in the "pocket" created by the holster was apparent.
I still carry an xd 9 service model nearly every day. The exception being if i am open carrying my glock 40 out in the woods.
I know lots of people have hate for the old school xd, but mine has been flawless through countless thousands of rounds. I prefer the grip safety for the purpose of re holstering appendix. I moved onto a glock 19 for awhile, and during dry fire draw exercises, i actually had a ND when reholstering when the tail of my shirt got stuck in the trigger guard. Luckily it was dry fire exercises.
For me, Appendix is the way.