One more time, as to the math. (.615/.550)²=1.25. Thus proportionate to bore dia a 1oz 28ga load is ballistically similar to a 1¼oz 20ga load. With longer shot charges efficient wadding becomes increasingly important to keep shot deformation at a minimum. 1¼oz loads in 20ga are put up in 3" cases. The 28ga standard was cut from 2 7/8" to 2 3/4" some yrs back, so to the best of my knowledge attempts of loading 1oz 28ga loads are all done in 2 3/4" cases. Space for good wadding becomes very limited. From a "Practical" standpoint unless your desire is for a gun of around 5¼-5½lbs, firing a 3/4oz charge, "All" advantage lays with the 20ga.
If, on the other hand, anyone enjoys walking the coverts with their 8½lb skeet 28, & handload it with only 5/8oz & it serves their purpose & they enjoy it, then walk tall & proud, it's no one elses concern. You wil though never convince me it is actually a "Better" set-up.
