A LFS I went to had a coral display with kessil, I was not impressed personally. Shimmer was good but corals looked drab. Maybe they didn’t have the settings correct because I do see nice tanks with kessil on the forum
My main issue with them is shadowing and the almost requirement to supplement with other lights.
Kessils can and will grow coral perfectly fine, but how they are used is the big issue. Drab looking corals could have nothing to do with lighting. I grew acropora perfectly fine with Kessils, but you're gonna need a lot to cover the area, so not really efficient by themselves, but I do think they're great when used with other styles of LEDs. I agree that most popular brands of LED fixtures for our hobby are overpriced for what they are and some are cheaply made. Quanta Helix bars (older version, quanta pro's) would be a great choice, along with Reefi's or Luca's upcoming Atlas fixture. GHL Mitras are nice, but I can't stand their software, but their hardware is one of the best out there.