I have the Dell 40 and it is a wonderful size  not too large at all. Oled is generally focused more on gamers so if you don't like its use for productivity that's why.
5k2k 40-45 is really the next wave of gaming monitors and will pair very well with the 5xxx from NV.

Stupidly large for a desktop productivity monitor. Dell has a 40" 5K x 2K and that is huge. AT least the Dell has 32" 4K ppi at 140ppi, this LG will be at around 123ppi. But it's size more than anything. I'd much rather a 34" 3840 x 1600 with 123dpi at least it'll fit on normally large desks, and not need to be curved unlike the 38" versions.