That is the exact rig that I am using.....as mentioned , not super fast, but is not as slow as many would have you believe....
There are many methods of drawing from the flap over holsters.
Over the years there have been many posts on the various methods...ie....cavalry twist draw, drawing the gun upside down and rotating, simply rotating the gun in the holster as you are at the loading table being summoned to the line...etc
I have used them all.....
Bugler