Debranding the phone means changing the product code with NSS. After upgrading the firmware with a newer version the original product code is set back, so the phone has the latest generic firmware, but the branding is still present. You understand now? Product code can be changed with Nemesis Service Suite (NSS). If you want more details for firmware upgrades, look on the N70 forum for the dedicated thread.
Debranded my phone with NSS from T-Mobile several months ago and updated to 5.06184.108.40.206. Then a couple of weeks back I updated to 5.0705.3.0.1 without having to change code again. Why would the code reset after updating?
Never had cause to use the backup but will try it later.
Phone seems more stable, ie no crashes and bluetooth performance is improved. I use TomTom 5 and I was having troubles with BT dropping out but since the update its been stable.
I didn't change the code back after the debranding/update.