Specific restore question - please help

[JibbyP]

Looking for sound advice please guys!

So, I jailbroke and unlocked my O2 iPhone 3G years ago and have been using it on Vodafone but it's got the point where the firmware (3.0 - 7A341) is just too out of date. Rather than me upgrading the jailbroken firmware I just want my normal phone again (because iOS4~ pretty much does the things I wanted my jailbroken phone to do in the first place).

Here's the crux. I want to stay on Vodafone but my unjailbroken/unlocked iPhone is locked to O2.
If I do the following, is this the solution to having a normal - up-to-date iPhone 3G?

Restore to factory with this:
http://forums.macrumors.com/showthread.php?t=603129

Use a free O2 pay-as-you-go sim (whack £15 on it) and use this:
https://www.o2.co.uk/apps/help/help?qid=1&q1=2&route=unlocking&case=Handset Unl

Would I then have an off-the-shelf 3G mobile that I can update the latest 3G-compatible firmware through iTunes... so Facebook and other apps shouldn't crash every single time, MMS will work and I can sync without fear of things going wrong???? I no nothing about basebands and haven't tampered with anything...does this affect me?

Thanks.

Any advice would be most appreciated. I

 

[j.dstasio]

I personally wouldn't want to use a 3G running iOS 4.xx.

The processor & RAM available on the 3G is just notsufficient. It's very slow and painful to use. You will immediately notice how slow and bogged down it becomes. I can't imagine why Apple made iOS 4 available on the 3G. The latest firmware I'd consider usable on the 3G is 3.13. Not all apps are compatible though so you kind of have to weigh what's more important to you.

Best of luck.

 

[JibbyP]

Thanks.

It's super slow as it is though.

My question was would the above process work correctly?