I have the 8k for a couple of weeks and received the 5k+ yesterday.
After playing a handful of my favorites games in the 8k, enjoying it a lot, I was curious about the supposed improved clearity and overall picture of the 5k+ in comparison with the 8k.
And, to make my point: I do not share the opinion of Sebastian (mrtv) for everybody to go with the 5k+.
Fist of all, the SDE of the 8k is ways better than the 5k+. In the 5k+ i can clearly see the black area between the Pixels. In the 8k it is also there, but much less, just like a faint idea of an SDE.
So I played Subnautica (probably the most underrated VR-Game - it is amazing in the 8k) for hours in the 8k, and jumped in yesterday with the newly arrived 5k+. I was heavily disappointed. Yes, the picture seemed „clearer“ but it was at the same time not as smooth and generally more „rough“ looking. So the aliasing in the distant was more obvious, resulting in a less nice picture (at least in my opinion).
I could not stand the now so obvious SDE, so I immediately put it back in the box.
After New Years holiday I will try it again in my motion rig. Maybe there it does have a benefit in running on 90Hz instead of the 8ks 80Hz… we will see.