David: I use 8-9 oz. shoulders for nearly all my holsters. For paddles, the holster itself requires some additional reinforcement to carry the weight of the pistol without shifting at the point where the paddle attached. I use 24-gauge galvanized sheet metal for paddles (readily available at most sheet metal shops, cheap, can be cut with standard sheet metal shears). I sandwich the metal paddle between two layers of leather, one layer 9-oz, the other layer 5-6 oz with rough sides out (this helps hold the paddle firmly in place by friction against the body and inside of the trousers). I also sew in a piece of the 24-ga. metal into the back side of the holster, extending down as far as practical and secured with the 5-6 oz. leather (placement of this piece requires some though so it doesn't interfere with the pistol's operating mechanisms, safeties, etc). Then I rivet the paddle into place with rivets passing completely through both pieces of the metal and leather covering them. Brass rivets will not damage the surface or finish of the pistol. The paddle, when fitted can then be bent over a mandrel to permit the proper clearance between the holster, belt, trousers, etc, and for the contour of the hip.
I make 10 to 15 holsters per week for my customers, but I only get a call for paddle-style on one or two each month.
As noted by others, positioning of the paddle is critical for the holster to ride at the desired angle.
Hope this helps you.
Lobo Gun Leather (serious equipment for serious business)