sogman I have owned 2 Pimax 8kx. The first one I had for a long time and bought it in the early times of it coming out. There was a learning curve for the headset. Like @fenderwq said about it being big. I did end up buying these weighted sand bags that you velcro to the sides so that the weight is even. It worked like a charm. I can now wear it for hours without any side effects.
Also I use a pillow to lay my head down on so I don't notice anything from the back of it.
Also it took my a long time to realize that you don't need the base stations for it to work. Before if the base stations lost site or whatever then the headset would go wonky. I ended up moving the base stations a bunch of times to try to get it perfect. Then finally one day I turned off that feature and bingo it doesn't need then for porn. You don't move enough for it to lose where it is in the room. No problems since.
One of the biggest things was that the first one I bought finally crapped out. So I went and got a Quest 3. I used it for 6 months to a year and kelp thinking about the Pimax so I bought a furbished used one from Pimax. This one is way nicer. Like @fenderwq said about the edges being blurry was true for the first one I had. It is not true for the second one. I'm guessing because it was made later on and they figured something out.
Over all the picture in the Quest3 is crisper and with brighter colors. But I notice the sides being a black ring of nothingness that all other headsets have. The second I notice it it takes me out of the imagination of being there. The Pimax is so big that it is almost everywhere you look. If you are looking straight ahead then you will not notice any black anywhere. It's a complete view of VR world. Maybe my eyesight is not 20/20 anymore but the trade off of image is well worth it. Also I don't watch many so called 8K videos because they all have the same problem with scaling.
I always vote for give me life size image over beautiful gaints.