I'm in the lump reducing (LR) ring camp, although I think LR is a misnomer. Like some of you said, it's more about lump management. I made my own solid LR ring with a surplus stainless collar, also found some scrap metal bands for making LR dividers in the future.
Here are few examples where LR shines for me:
1) cramped indirect cook - no worries of charring meat that overhangs the PS
2) using Large's AR in the XL - it's like matching the pan to the stove element size
3) cooking kebabs - smaller grids can rest directly on the ring, over concentrated and level lump bed
4) high temp non-raised direct tandoori chicken cook - creates a perimeter buffer to avoid over charring
IMO Law of conservation of energy makes sense for long low and slow cooks, but how practical is it in the above scenarios?