Its legal, and it will only mess it up if you do something wrong. 99% of the time there is a fix. I'm sick of my D2 as well, even after hacking it but I'm picky. Anyway, hacking/rooting is generally pretty easy, and you'll get a lot more out of your phone. When I say I still have issues after hacking it, that's probably because there's something a lot deeper. I wouldn't worry about insurance either. You can just erase traces of root and nobody will every know
... Hope this helps.
Sent from the future using my Galaxy Nexus!