I'm comparing the TX-RZ610 to the TX-NR777. There are two differences I'm concerned about; the first, and there's no clickable link for me to find information via the Crutchfield website, for the HDMI to HDMI Upconversion. What exactly is this? Does it really matter when I plan on having my PS4 and a future 4K Blu-Ray player hooked up to it via HDMI? The only other sources be a VHS player hooked up via composite? The other difference I'm concerned about is "HDR-compatible" section. The RZ is HDR10, while the TX also has Dolby Vision and HLG. Is Dolby Vision taking a strong enough early stance that I should worry about future proofing? I won't be buying for another month so no rush. No to mention, I won't be upgrading the TV until the holiday's at the earliest. If you can point me in the right direction for information on these, I'll be happy to research, but I trust the opinions on these forums, so I figured I'd start here. Thanks!