3GS jailbroken and unlocked on 4.1 with ipad baseband - how to upgrade to 4.2.1?

[GZZZzzz]

Hello,
I'm wondering if it's possible to upgrade to 4.2.1 without any problems since everything is working fine now.
I don't know if upgrading is risky. Can it cause losing my unlock (non iPhone SIM working fine right now).
Could you please advise?
Thanks a lot in advance.

[iYeow]

It is not OK to go for 4.2.1, if you want you have to restore to cfw of 4.2.1. You have use use Pwnage tools 4.1.3 and add the 3gs bundle. If you have the new bootrom ,it will be tethered and you will have to use redsn0w to jailbreak and the end result is battery will drain out in a day without the phone being used. I have already experiment it myself.
If you want to do it, go ahead and you will see what i mean.
I suggest you stay at 4.1 and be happy until a better jailbreak is available.