Wanting to jailbreak my iPhone running iOS 4.2.1 but I've got one question. Say I jailbreak it and in the future want to unjailbreak it. By then, the new version of iOS 4.3 will be out. Will I run into any troubles unjailbreaking since my jailbreak is running off of iOS 4.2.1, or can I just restore/unjailbreak and go to the normal iOS 4.3?