>1- A 4K screen does not still my hunger. I can only show 4 FULL HD screens on there. 2x 4K screens will be painful to use comfortably as you would have to turn your head way too much. If there were 49" 5760 x 2160 curved widescreens I might reconsider, but those do not exist (yet).

If you keep them vertical, you don't have to turn your head left-right so much. And you're also saving on vertical movement by not having the gap between the top and bottom row.

>2 - Those 6 screens are independent from each other. I can run each monitor on the resolution and DPI settings of my liking, which is a bonus as we are in the process of making our app DPI aware. Having windows snap to the boundaries of the monitor without extra tools is a bonus.

OK, that's a solid reason.