Your 570 pattern looks nice and even and a quick count reveals around 110 pellets in a ten inch circle.... The 20 looks good and even.. But it would not satisfy my buffer zone..
Going to the twenty we all make sacrifices some choose to sacrifice margin for error and others will choose to sacrifice range.. I did not switch to a 20 to sacrifice range, I am not a long range bomber, but I want to be able to shoot a bird at 40 and have some buffer beyond.. Thus I have chose to ignore the 20 inch circle and look at a 10 inch and the 4-5 inches outlying that circle, due to the above posted math.. If I cannot kill a gobbler with a 15 inch halo, I do not deserve that turkey.. To satisfy this and my buffer zone I wanted pellet counts in the 140 to 150 range not the 180-200 range that many seek..
Both Tempest sucked in all three guns I shot at satisfying said requirement.s