You can get the same panel from Dell brand new for the same price as this refurb.
The dell has an IPS panel this is a va panel.
I don’t have any experience with curved monitors; but I do presently use a flat 29-inch 21:9. I will not go back to standard widescreen. As for the 29-inch size, it is, if anything, too small. It seemed enormous, at first; but I’m realizing that one cannot easily have too much screen. Going ultrawide is definitely preferable to dual monitors, especially if using for both work and recreation. I can’t be certain, but I don’t imagine I’d experience any benefit in a curved screen at 29-inches; but at 34-inches, I could see the advantage. But again, just speaking for the size and aspect ratio, I promise you won’t be disappointed.
What is the return policy on these?
Our return policy is linked in my signature. 
My monitor is a VA panel and I love it for media and games, the blacks are just beautiful. However, IPS tends to cost more, so if the Dell is new and IPS, it’s a better value than this monitor all else being equal.
So are dead pixels or excessive light bleed considered defective or damaged?
You would contact Samsung first on the dead pixels as they carry the warranty. You can contact Samsung to see what their dead pixel policy is.
I called support for information on warrantying dead pixels, for the 27" a return is authorized when you have 17 dead/stuck pixels under the new warranty and the rep verified that the 90 day refurb warranty has the same number as a criteria.
I’m not terribly pleased about that number, but they did answer the phone very quickly and while it did take some time to retrieve the info specifically on the refurb warranty also they were good about it.
I would assume they have a higher number for the larger sizes but since they had to put me on hold for each question I asked I didn’t check on that.
Why do they say 21:9 aspect ratio rather than 7:3?
Maths are hard.
I presume you already knew; but for those who don’t: It’s much easier to compare 21:9 with the common 16:9 format. Because like manhandsha said, maths are hard, and 21 are bigger than 16. Now if those were cookies, you’d have, well, more cookies. So 21:9 is clearly the better choice. Or else you hate cookies.