My personal preference has always been to wear a shoulder holster for concealed and a hip holster for open carry. My thinking is, A shoulder holster makes it easier for a charging bad gun to point my gun at me. Where as a hip holster makes it easier for me to point at a charging bad guy. If I am carrying concealed, my gun is better protected from the hands of said bad guy. As for somebody sneaking up behind me and grabbing my gun... Yes it can happen, but a little bit of situational awareness is enough to prevent that. A high retention holster helps as well.
Welcome to OCDO, and greetings from sunny, dry Arizona!
Situational awareness is your best defense, second only to the pistol (the argument can be made that the two exist in more of a symbiosis, specifically mutualism, in which one reinforces the other), and if I may add to that, the buddy system (when possible) also seems to help increase awareness of the surroundings (best case: buddy is OC as well).
Only dissenting comment in response to your post is that while a concealed pistol
is more secure from an intended, planned-out gun-grab, it may not be safe from an illicit exchange of ownership, if ya know what I mean. All that needs to happen is for you to be targeted for looking like an easy (read: UNARMED) target, blindsided by a cheap shot (such as the Knockout
Assault we've been hearing more of lately) and then relieved of your pistol while you are unconscious or dead.
As to the OP: I don't particularly like shoulder holsters, and I'm not comfortable with sweeping my arm (lots of places on it I'd like to keep intact, like the bones, nerves, blood vessels, muscle tissue...) in a high-stress environment. I know training is the key to proficiency, but the rule about not pointing your muzzle at anything you're not willing to destroy seems to be there for a reason.
Looking into crossdraw though for when I have to ride in a car or sit in more constrained quarters.