No offense, but its a bit difficult to trust someone who’s never spent $4000, or a single penny at all for that matter, on such large penabled screen.
On a totally unrelated note, it’s also not worth it to get a headphone that costs more than $25. Trust me, because I cant afford spending more than $20 on a pair of headphones /s
A 13" laptop and 10" Wacom tablet is also cheaper than a fully specced Eve V, because on-screen digitizer, the adjustable hinge, etc. dont come for free
E-mail are often set up like a web page, or has some contents that requires some detail, especially if we are talking about collaboration with engineering or programming team. There is a reason why technical books are made in A4 size. Of course, for standard text, a 4" screen will do just fine.
In addition to that, multitasking my come into play here. My iPad (9.7") is big enough, as long as I dont have more than one app at a time. Once I put another app there, it gets cramped in there very quickly. Putting the OS aside, while I prefer the iPad screen for one app at a time, I much prefer using my 12" Surface for having multiple apps on the screen (even something as simple as snapping a music app)