Dunno mate but I got the XD70 and apparently that doesn't have proper HDR but the PS4 games look and play excellent

Nope, no difference at all. I've no idea where the obsession comes from. Compare the LG UH850 and UH950 or the Samsung KS7000 and KS8000 in areas that it might affect such as colour banding.

There are big differences between HDR performance but the important hardware influence is the backlight, aspects such as it's colour gamut and local dimming abilities.

This XD80 doesn't have local dimming so it's not much of an HDR TV as it can't display a wider brightness range on screen. You really need to be looking at 90 models in Sony's range like the XD93 or XE90 if HDR is important to you.

How do I get there? I'll give you a fiver.

Can confirm the OS can be laggy (I have the very similar 49" XD83 model), however for the most part works well enough. This is my main gripe with the set, followed closely by the light bleed (it's a lottery, my friend has same model with no bleed). However, for the price, build and picture quality it's hard to beat. I've kept mine for this reason despite the above issues and knowing full well the "HDR" presented is a poor representation of what can be achieved.

I don't have a PS4 Pro (yet) but the standard PS4 looks amazing on it.