Take if from me, I've tried some factory stuff from Bianchi and Safariland. Both are serviceable, but if you really want the shoulder rig of your dreams call Sam Andrews in Florida. He's done two for me and if it's cold enough for a jacket I've got one of them on. Sam can configure them almost anyway you want.
My revolver one is for my .41 Magnums and sports three horizontal speedloader pouches and a knife sheath under the other arm.
My auto one is for my Glock 20 and sports a spare horizontal magazine pouch under the holster and three more under the offside with a knife sheath behind them.
Both holsters and pouches are cordovan and carved with a fancy basket stamping. The holster has my initials on it. Very cool to me.
Lots of equipment...right? Well, it's still comfortable after ten hours. The secret is the harness. Everything is a soft suede including the connector that holds the straps together. It's also wider across the shoulders to distribute the weight evenly. Lastly, it has an additional horizontal strap on the lower part of the harness that keeps the holster from moving forward when withdrawing the equipment.
Trust me, this one is a keeper.
Lastly, don't be afraid to suggest an idea if you have one. Sam runs a custom shop and loves to try new ideas.