Its not just a matter of doing 'HDR justice' unfortunately. TVs that cannot get bright and don't have good enough local dimming cannot display HDR without adverse effects such as the picture being too dark, or it being washed out.
Its all to do with tone mapping and the master/director intent. Squishing down 1000 nits masters, or worse 4000 nits to lower nit levels does not work well. Although perhaps in some titles it will be ok.
With an OLED you're into a different territory completely, assuming of course the newer 42" OLEDs will mimic the 48" models. 700 nits whilst not being up to the 1500 of high end LCD TVs is not as much of a disadvantage due to an OLEDs ability to individually dim each pixel, and display blacks as total black.
The XH8505 is a very expensive TV for what you get. You're paying a premium fee really for a 120hz panel. The TV still falls short with HDR picture quality due to low peak brightness and lack of local dimming. Whats more, at 43" the TV is using an IPS panel instead of VA at 49", and therefore the contrast is abysmal.
In my opinion if the OP does want to change TVs he should first determine which panel type is suited, IPS or VA. Then take the choice from there. Its a good idea to spend little rather than more due to the problem these TVs will all have displaying HDR content and its also advisable to pair the TV with an external smart system so you can disable HDR on the HDMI port.
Its becoming harder and harder to recommend small TVs because its harder and harder to avoid HDR nowadays. If the OPs usage doesn't include any HDR at all - perhaps only broadcast TV then its not important, but if they like most people want an avenue in to the world of streaming and HDR then buying a smaller TV is not a good idea at all.
I understand what you mean by conflicting advice, but didn't you, yourself also come to the same conclusion I suggested? That you needed to opt for a bigger TV to get something worthwhile?
I trust from your recent comments that you've been happy with that decision. If I'm being honest, I'm not sure you'd have been happy instead going with a 43" model.