I bought a new iPhone 3G off of Craigslist and it has software version 3.1.2 on it. I know there were issues with the 3G running poorly on iOS 4. My question is has this been resolved in 4.1 or should I keep the phone in 3.1.2. I don't jailbreak or unlock I just want whatever runs best. Also a couple apps I like will not run because of the current firmware version.