Upgrading an unlocked 8900's OS ( O2 uk )

[skidilydidily]

Hi, I have a quick question regarding upgrading my phones OS.

I brought my phone its an 8900 off my cousin a few months back, he brought it on the orange network in the uk. I got it unlocked to O2 and registered on the BB network etc (BIS) my concern is if i do update to this OS version will it still work with the network ok ? does anybody who has unlocked there phone themselves in a shop know? who has actually upgraded there Os aswell did you run into any problems? i do have the MAC? code i made the chap in the shop write it down for me,

Shall i just go ahead and upgrade lol? thanks in advance!

*EDIT*

Also i have downloaded the latest officail release off the site, hutchinson (east asia), does this make any difference putting it on an old Orange now an O2 decive, and it will be english correct?

[freethisberrydotcom]

DO the upgrade but backup before. You're device will remain unlocked.