Just trying to understand what is going on behind the scenes. Here are the facts that I understand. You must have a SHSH blob saved to get iTunes to allow you to (after bypassing their servers) downgrade. Those signatures only happen when that firmware is available. So if you bought an old iPhone in the box running 3.0 you can only get Cydia to save the most current firmware in the wild. However, if you have a 3GS on the old boot rom and a Pwned iPhone you can make custom firmwares and then update/downgrade without using Apple's servers at all. What is it about the Pwned iPhone that allows that (why does iTunes allow you to bypass the signature verification). And is there nothing that could happen to your iPhone that would remove that code that allows it? What if you used BlackRa1n before, can you make a new custom firmware and update the same as if it had been Pwned?