upgrade to 3.1.2 on unlocked/jailbroken iphone 2g

[gescare]

I have several questions and before posting this I swear I did my research however could not find anything that would lead me to think the process is easy or worthwhile.

I plan on upgrading my fiancee's iphone 2g to 3.1.2 using a mac. Her phone is already jailbroken and unlocked and running 3.0.

I have read numerous posts stating how they have run into issues when unlocking and jailbraking the phone on 3.1.2. However I was under the impression that if your phone was already unlocked/jailbroken, you wouldnt lose the unlock or the jailbreak and that all you needed were the file and you would be good to go.

Given everything I have read I dont think it is that easy.

Can someone please shine some light into this inquiry?

Thanks

[i.Annie]

You will always lose the jailbreak if you upgrade. Being on a 2G you technically won't lose the baseband but the unlock can easily be re-applied. I'm not sure how that works on a 2G but to answer the jailbreak question yes you will lose it in the upgrade so you'll have to do it again with blackra1n or pwnagetool if you have a mac.

EDIT: blackra1n for mac too but pwnagetool is for ONLY mac. blackra1n is faster but people report more problems with it. I haven't had a problem with it myself.

[gescare]

I have a mac, so should I upgrade using itunes (9.02) and the stock 3.1.2 software from itunes. Then use blackrain and make it rain, then use cydia and install bootloader? Or should I just use pawnage and create the custome firmware?

Ive heard bad experiences with both.
For the first Ive heard having to use SSH and diskaid to delete somefolder from the Iphone's files since the bootloader is not working.

Using pawnage I have heard that people cant get the phone into recovery mode or DFU mode (however I dont think you need DFU mode since my phone is already jailbroken and unlocked).

I just want to make sure I can accomplish this tonight since this my girl's phone and dont want to piss her off.

Upgrading/unloking my 3gs was so easy that reading all the horror stories from the 2gs makes me want to stay on 3.0.

[i.Annie]

Just don't overthink it. Make sure you back whatever you need up. Download blackra1n and run it. Takes less than a minute. Open the app blackra1n on your phone, install cydia and/or rockapp then in cydia download bootneuter to unlock. If it fails for some reason just downgrade and use redsn0w (it should be ok if you do everything right which isn't much lol) if anything the 2G should be easier than 3G or 3GS so don't worry.