Thanks a lot. This is my wife's phone so she'd rather not to update if a data wipe is required. She's actually quite happy with 4.1.
Anything extra would only be a "good to have". I think I'll keep it on 4.1 until she switches to another phone.
I did download the slightly customized stock rom so that it could be updated in the future.
In fact, I still have stock recovery and the only reason I rooted was to disable carrier iq because it was doing funny things with the GPS, very annoying.
There is no other way to disable carrier iq without rooting...unfortunately...
If you flash that ROM over her current stock ROM, it should act just like an OTA update and replace the JB OS with the KK OS. It should also replace JB version Google apps with KK ones too.
If you decide to do this, you will need to do 3 things:
1) Make a backup just in case, but then copy the backup to your PC
2) Backup the internal SD to a PC and then format the internal storage. (see *2 below as to why)
3) After the flash, you will need to install the apk from the following thread and use it to install a Kitkat compatible CWM. If you don't while in recovery at any time, you may get stuck in what's called the Recovery Bootloop. Basically, every time you try to reboot the phone into the system (whether from a powered off state or from recovery), you will always go back to recovery.
The only bad thing about this recovery is that it can't read external SD cards, so anything you want to flash/backup will need to be stored on internal storage.
*2) Kitkat uses a different directory system for internal storage. If you were to not wipe the internal SD and managed to get the OTA working, it would wipe the drive for you automatically (which means all your data would be gone!).
However, with this flashable stock ROM, what will happen instead, is that all your data will remain, but will be hidden from view/access. If you have root, you can get it and move it, but it's a pain. Otherwise, your files are hidden from you, yet the system reads X amount of your internal storage as being occupied by "Miscellaneous" files, yet shows that nothing is there.
So just backup the files, then format the internal storage (which will leave her apps alone) before updating. Then flash that ROM and then copy the files back over.
All this is up to you and your wife as to whether or not you deem it to be worth the effort.