I'm in a bit of a special situation here and I'm not sure how to proceed. I've been researching for the last few hours and am still a bit confused.

Background: I have the original release iPhone 3GS and have been jailbroken (and not unlocked) since its release. I'm assuming this all means I have the older baseband. To jailbreak, I think I used redsnow once, and pwnagetool once. I'm now jailbroken on 3.1.2.

My problem is that my iPhone is totally hosed and needs to be restored. Since 3.1.3 is out now I'm not 100% how to proceed:

- Should I upgrade to stock 3.1.3 via iTunes and then use one of the newer jailbreaks (spirit, pwnagetool 3.1.5?) to jailbreak? If I upgrade to stock 3.1.3 will my baseband be upgraded and will I be out of luck -- will I be able to jailbreak at all? I've read conflicting info on this.

- Should I upgrade to stock 3.1.3 via iTunes and then downgrade to 3.1.2 and then jailbreak with pwnagetool or by some other means? I think my hashes/blobs/whatever are stored on Cydia, so I think this is an option?

- Can I somehow restore directly to a custom 3.1.2 without upgrading to 3.1.3 at all? Or can I restore directly to a custom 3.1.3 without having to restore to stock 3.1.3?

Some other questions/concerns:

- I have the tethering hack installed and would like to keep it or install it again, if this matters

- What is the current wisdom on restoring as new or restoring from a backup? I've read conflicting advice on this.

Long story short, I need my phone for work and personal reasons and need to get up and running tonight. I'm nearly at the end of my rope and am close to just upgrading to stock 3.1.3 via iTunes and forgoing jailbreak altogether (though I'd rather not do this if at all possible).

Any help would be much appreciated and I will be in your debt!