I'm currently running 5.1 iPhone 4 on a teathered jailbreak. I have had the jailbreak for about a year and have only had to do a just boot maybe a total of five times. U just gotta make sure u don't let ur phone die. I've been satisfied with the teathered version and didn't wanna teathered version as first but now have no desire so rejailbreak just to get unteathered. But that's just me.