Yes and no. I just tested again... 4K is considerably crisper than HD, even when resizing down ~25% and up to ~60% of original size. The main problem is actually the size... 4K is just too large of a screen area to be viewed without having to pick up the controllers to move the virtual screen around. Anything past the bottom or right half is more or less off-limits, meaning you have to move those windows (e.g. builds)... or just resize the editor to the upper-left corner.

The best setup I could manage was to put the bottom of the virtual screen a bit in the floor, then you are looking straight on so that you can see the upper-left corner and still get to the menus and see at least the first ~25 lines of code (Consolas size 10).

I should note I'm using the built-in Desktop which you can insert via Steam VR Home. I just dropped it into the default home and moved it around/resized until I found it workable. There may be better tools for running virtual desktops in VR, I haven't explored this space at all since reading anything in any VR app for more than a few minutes makes me dizzy... speaking of which, no more VR for today! ;)