Upgrading iOS on factory unlocked phones

[LuckyTommy]

I've got a factory unlocked iphone 4 and I'd like to upgrade the OS.

Right now I have:
fw 4.2.1
bb 03.10.01

So after the upgrade I'll have:
fw 5.0.1
bb 04.11.08

My first question is, is there any risk by doing the upgrade that I'll lose the factory unlock?

Also, since there is currently no unauthorized way to unlock bb 04.11.08 and going there is a one way street, lets suppose I do the upgrade while preserving the baseband to hedge my bets. Do you guys think that might ruin my factory unlock?

Thanks.

[MiaField]

What? If you bought the phone with a factory unlock shouldn't you be ok to update anytime you wanted?

[Simon]

If it is factory unlocked you will be fine. No need to preserve your baseband.