Welcome aboard on your first post. Both are outstanding vendors. I have bought loads from each. I plan on buying a flat of 16 gauge Vintagers from Polywad next week.
RST has a larger selection of loads in each gauge, but Polywad has exactly what I need. In 16, I like the 2.5" 7/8 oz. #7.5 from Polywad for quail, dove and woodcock. I haven't bought 12 from Polywad, but have from RST. I wanted to see how the felt wads rather than plastic wads worked out in one gun and RST had them. Polywad didn't. In keeping the old "girls" safe, it's not just chamber pressure of the load that is a consideration. Recoil, a product of mass and velocity, can be the enemy of a 100 year old gun stock. While the guns may have been originally designed to handle heavier loads and velocities, sometimes it is best not shoot them. Gil