I agree. Unlock your bootloader (Doesn't void warranty on Developer Edition), flash TWRP recovery, then boot to TWRP and install/flash SuperSU. And it doesn't matter what ROM version you're running. (there is a TWRP for 4.2.2 and one for 4.4/4.4.2).
As mentioned, the bootloader included in the android versions can prevent you from downgrading the rom version. (i.e. bootloader in 4.4.2 prevents you from downgrading to any previous ROM). Why would you want to downgrade? If you have a locked bootloader, you'd want to downgrade to be able to use the root processes needed when you have a locked bootloader. But if you have an unlocked bootloader, because you can flash an alternate recovery (not possible with locked bootloader) and root no matter what ROM version you have installed, the only reason to downgrade would be if you encounter a bug you can't deal with that isn't present in the older roms.
because 4.4.2 fixes the exchange and bluetooth issues, and doesn't introduce anything new, its suggested you update to 4.4.2 if you have an unlocked boot loader (4.4.2 isn't rootable on locked bootloaders and may not be, so its recommended that those with locked bootloaders who want to root stick with 4.4).