burn-in isn't a that big of a issue anymore with the 2nd gen QD-oled. Woled is even better.
i haven't personally witnessed much dark grey uniformity issues but there are reports that it's panel dependent.
HDR brightness so far seems to be a OSX issue, on windows 11 HDR works like magic.
build quality- again it depends how rigid of a standard you are telling the suppliers, the ones in alienware is pretty high.
i went from 218ppi to 140ish ppi and the trade off is only noticeable if you sit a foot away and try to make out whatever blurriness there is, once you get accustomed to it you won't even know its there.
OLED burn-in - less intense of a problem nowadays, but it's still a cumulative effect. RTings has an ongoing longevity test that shows the latest gen OLED Panels still suffer from static content over time. Part of the improvement is just manufacturers using better compensation algorithms, which has the cost of lower brightness over time.
I own a 2nd gen QD-OLED TV that I don't baby, but I won't be shocked if it develops noticeable issues over its lifespan. I would not feel comfortable displaying static UI stuff from my Mac for many hours a day though.
HDR Brightness - OLED monitors currently can't get anywhere near as bright with specular highlights and especially full-field versus miniLED. I suppose that doesn't really matter in darker rooms or if you're not trying to grade HDR video though. One thing I appreciate about the Studio Display is that it gets plenty bright enough to use in a bright space.
PPI - Do you use non-integer scaling on your OLED monitor? 4K looks completely fine @ 1080p HiDPI, but once you scale to 1440p text takes a noticeable hit on MacOS.