My friend said there arent any jailbreaks available yet for 4.2.1 aside from the tethered one which means I have to have it plugged to a computer for it to work. His iTouch is jailbroken but its version 4.1. all he told me was you will lose some features that 4.2.1 has and 4.1 doesnt but he didnt tell me anything about it breaking. Im just scared that i wont be able to open my itouch anymore if I downgrade it.