These differences are very clearly noticeable. I upgraded many years ago from a 72% sRGB to a 99% sRGB Dell IPS and everything looked much better. I just got the LG 27GN950 which is 95% DCI P3... I was mainly getting it for the 4k/144 with the P3 as a nice bonus (I already had 4k/60 on the Dell). Looking at the Dell, I was thinking that P3 might be nice to have but it wouldn't really matter much aside from photo editing - the colors on the Dell already looked great.

I just unboxed the new monitor 2 days ago. The richer color was immediately noticeable, and when I looked at some random photos I took with my phone recently I was blown away by just how red and green and yellow/blue things were. Like a completely new realm of color.

It's one of those things that you can't appreciate until you experience it (same going from the original 72% to 99% sRGB).

The Dell was $450 for 4k, 2.5 years ago. The new LG was $800, but you can find 60fps P3 4k monitors for around $500 these days iirc. If you're on Hacker News you probably use your computer a lot. Unless you're running low on cash, upgrading to a great monitor is worth it.