If you are still on 4.2.2, then I would recommend to not upgrade to a 4.3 stock rom. Doing so will flash the new bootloader which will setup Knox on your phone. When you have the new bootloader and you flash a custom rom, Knox wil be set to 0x1. You can read more about Knox in the Knox thread.
If you planning on flashing custom roms in the future, then stay away from official firmwares.
Samsung Galaxy S 4 I9505 | WanamLite v1.5
Samsung Galaxy S II I9100 : AOKP 4.2.1
HTC Touch Pro2 | ROM: Valkyrie 6.5.23115TR2.5
HTC HD2 | DarkStone1337 [FroyoStone Sense - V3.2]
HTC Desire : Oxygen v2.1.3