To update or not to update, that is the question.

[johndoe25]

A friend of mine got a used 3G on 3.1.2 unjailbroken, but will be jailbroken. Is it worth it to update to 4 point whatever or stay on 3.1.2.

[Mes]

Did you or your friend save any SHSH blobs with Tiny Umbrella?

If not, then you can only restore/update to the currect 4.2.1, or any 3.x version.

You didn't mention unlock. Need/want any SIM usage? If yes, you must use a custom firmware for 4.0 and above (I would use for all versions, to made sure baseband is not undated)

3.1.3 is acceptable on a 3G, 4.x will be slower.