Well, the key differences as I see them would be:
1) 6 HDMI 2.1 inputs (8K/4K120) vs 1 HDMI 2.1 input
2) 4 independent Sub outputs
3) Direct Live upgradable in March 2023, DLBC upgradable sometime in 2024
4) 1080p on-screen-display vs ancient 480p
Lastly, have you considered the 3800? Given that Denon has added both independent amplifier disconnect and Auro3D to the 3800 -- features previously exclusive to the 4xxx series -- it seems you could go with that model for $1700 and be substantially future-proofed relative to the aging 4700.
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