Brilliant write-up, Dem
Apocalypse Now is a great film, one of my favourites, and one I've seen countless times.
The 4K release is outstanding, with the AV quality, on the 4K Ultra HD discs noticeably better than the (admittedly impressive) Blu-ray discs. The HDR really makes the colours 'pop' and accentuate the contrast levels, with the Dolby Atmos track being as good as you accurately described. The object-based sound is impressive in making the action sequences seem even more violent, and the sprawling Kurtz compound seem uncomfortably claustrophobic and horrific.
In part of a review I wrote many years ago, I said:
"The making of 'Apocalypse Now' is almost an analogy for the Vietnam war itself: Americans, full of money and ambition, travel to a distant country that they know nothing about believing things will run smoothly then find that what can go wrong, does. Coppola even admitted afterwards that "we had access to too much money, too much equipment, and little by little we went insane." Martin Sheen had a heart attack, Francis Ford Coppola had a nervous breakdown, Marlon Brando turned up 100lbs overweight and not having read either the screenplay or 'Heart of Darkness', several members of the crew were kidnapped by Filippino guerrillas, the shoot was set back by a typhoon and ended up lasting over 200 days and costing over $30 million, nearly bankrupting Coppola. It is probably for these reasons that 'Apocalypse Now' resembled the chaos of Vietnam more than most other films about the conflict and is the finest Vietnam War film and one of the greatest war films ever made."