Just got a new Ipad with 4.2.1 and heard there was an untethered JB coming up for it. Problem is, from what I've been reading we need to have some backup stuff saved from previous versions to be able to use it. My question is, having bought it with 4.2.1 already, will I be able to use this untethered jailbreak or should I just go for the tethered one?