i would say it was safe. I am on O2-UK which has a pathetic 500mb DL limit which is ridiculous considering a pay an extra £5 a month for "unlimited 3g" and what really gets me mad is that if you get the iphone on the same network there is no download limit.

i haven't had my 1st bill yet so i don't know how much extra they will charge me but i think i am considerably over 500mb