Little bit surprised by some of the comments! I know for a fact that my company got a nasty gram from the FAA for exceeding the 250 below 10 out of ORD, even though this was below our min clean speed!!! This was flying a B747. We got a company note to specifically ask if we could fly faster than 250, if not granted , we had to climb out with flaps 1 out of 10.000! Strangely enough, the states where the only place that would be difficult about it. All the places in the world would not care if you exceeded the 250/10.000 rule during take off at heavy weights!!