I think I'm biased due to my personal experiences with all of my H&R USHs. I bought the first in 1995(?) and shot Remington Copper Solids. It took a lot of slugs to get it dialed in. It would shoot pretty well but getting a big ragged hole from 5 at 100 - 150 just never happened. They killed deer real fine cuz they hit the vital area.
I tried some Brenneke Gold Magnums and my groups were outstanding. Ragged holes became reality. Putting deer down with these was awesome. They hit really hard and I could really deliver a shot where I wanted to. I never went back and my old barrel looks like new. There is no fouling in there and I have never had struggle to clean it or use any special solvents to release lead.
Over the years I have bought 3 more H&R USHs giving me 2 12 gauges and 2 20 gauges. They are all shooting Brenneke and shooting fantastic. In 2007 H&R went to the Ultragon rifling which doesn't have the sharp edges on the rifling and there are 6 lands/grooves and a 1:23" twist. They clean right up too.
Anyhoo. Bottom line is finding whatever each gun fires the most accurately and stick with it. I get a real snicker when guys want to switch to "that new slug" every year or 2(usually a sabot). Advertised as faster......more accurate......more powerful......more knockdown......more money and they usually get all frustrated with worse results from their previous choice.