My initial thought was that the video & audio side of AV discs has moved on so far from the relatively modest abilities of DVD that you're really missing out on the latest tech. I only recently bought a 4K projector so I'm new to the world of 4K discs but I'd say there's a as big an uptick between Bluray & 4K Bluray as there is between DVD & 1080p Bluray. Not to mention the move to object-based audio. Now you might well not want to move to object based audio but you appear to have some quite serious kit that could really breathe when fed with higher resolution formats. But you know that already and perhaps you prefer the sound from your 800 on DVD & are happy to accept the 'compromise' on the video side of things.

Cinema: Meridian 271, 3 x DSP640 (behind screen), 4 x DSP320 (in-ceiling), 4 x DSP3100 (surrounds), 2 x AC12 (interface). 2 x Perlisten D12s subs, Lyngdorf MP40 processor. DT 145" 2.35 AT screen. Sony VW870 projector & S-T lens, Lumagen Radiance Pro.
Lounge: Roon, NUC, Kef LS50 Wireless + 2 x REL Gibraltar-2 subs

Meridian owner since 1998