To each his own as I've mentioned. But there's a reason LE and military place the firearm in the "HIP"... And without getting into a divergent discussion as to how you cannot protect a front more than a side in an attack, it is totally easier.
Your example of sneaking up on someone from behind is the same for a frontal carrier because if someone attacks you from behind, your appendix carry is just as much a disadvantage. Fact is "most" attacks are from the front, as is 80% of attackers are "right" handed, firearm in my left hip (also right handed) keeps the weapon the furthest from an attacker. And rotating a hip away from an attacker (frontal) is much easier and requires mess movement than protecting the front. I could show you physically how the body works, and how it is easier to move (rotate) to the side, than apply physical force trying to maintain the center. These principles, don't change for anyone, they are what they are.
Honestly, a question for you... when you physically "square" off with someone do you stand actually "square with them? Just curious... Because that in itself, your body/mind natural reaction tells more than I can writing here. But hey, what do I know...
Like I said, what works for you, great!
