Bit of a random rant, but despite being so common, 27” at 4K is a really poor combination for a computer monitor. At 1x scaling, everything is too small, but at 2x scaling it’s far too big. So you have to go for a non-integer scale, which on macOS at least results in reduced image quality and graphics performance (it renders to a different sized frame buffer and then scales it).

The ideal is 5K, which is double 2560x1440 in each dimension, but essentially the only 5K displays available are the LG one made in partnership with Apple, which is over a grand and has numerous quality issues, or the one built into the iMac. It’s really annoying.

I like that Dell display (I mostly use Dell and LG displays) and most people should certainly save the money. The areas where the specs aren't the same are really significant though (e.g., resolution, as you noted, is a major difference despite only being one of the specs. Brightness, dynamic brightness, and size are also quite significant and drivers of major cost differences in just about any monitor comparison.)

Here's a spec overview for those unfamiliar. https://www.displayspecifications.com/en/comparison/4f37c07a...

I use a UP2718Q every day (used to use two of them).

Did you just compare that mediocre POS to an XDR?