A chest rig is definitely the way to go, especially if you are wearing a pack with a hip belt.
I don't really notice weight worn on my chest. On the belt, it becomes a problem.
When hunting grizzly country, things can happen fast.
If you are working up an elk, you will probably not have time to retrieve a rifle or a pistol, if it is not on your body.
As someone who lives over 1,800 miles from the closest wild grizzly, I know that I will not practice with bear spray and would probably not pay attention to wind direction at the moment that I need it. (Heck, I don't even know how to get it in Georgia, USA).
Bear spray didn't work out very well for the couple in B.C. last year...
I don't have a Hickock45 setup in my back yard (I wish I did), but I do have a swinging steel target.
I practice with my pistols, but I've never even pressed the top of my wife's Mace.
Love the idea of a chest rig!
In some of my applications (bushhogging on the tractor), I would want it to be as light and unencumbering as possible (I carry a .22 revolver, in that situation - loaded with a combination of shotshells and regular bullets).