Yes I have done it.
I also have the NEE (Nordic) S4 Active, I tried both with the Stock 4.4.2 NEE from Samfirmware.com and the PHN 4.4.2 ROM of mythi's.
I am now running CarbonRom 4.4.2, and also tried to restore 4.2.2 Stock.
The only downside being that if you install 4.4.2 and restore a custom ROM after that you will get a red line when booting saying "KERNEL IS NOT SEANDROID ENFORCING".
So you can go ahead full speed and try it, works like a charm!
My problem is that only updates what i have installed are samsung stock updates, so i haven't never used odin or flashed anything in my phone.
After i updatet my phone to 4.4,2. ( i think it was last week) some of apps stopped to work
Now i'd like to downgrade it back.
I found some instructions that only thing that i have to do is flsh 4.2.2 with odin and i'm back to jb.... it did not work. And now i' back to kk...
But if i use your instructions to root my stock 4.4,2 and after that i flash stock 4.2,2 NEE Rom i' m back to JB.
Can you also type simplified instructions (with downloadlinks) how to do it... it's my first time.
Thanks so much!!!