I have the 80 and it's had issues with 4k discs that are not perfect. Ready Player One had a bad skip/stutter scene near the end, cleaned the disc and it did better. Similar issue with the incredibles 2, where it had some minor scratches and skipped.
I got mine on a great closeout deal, so for now I'll keep it. But I probably will look to upgrade to the Sony in the future. To note, this player has done flawless with blu-ray, so I'll probably move it to the 1080p TV when the time comes I upgrade.
Denon X4300H; Sony XBR75 900E; Definitive Technology RLS-II/DI 5.5LCR/DI 5.5R; NHT SW12