SNS3Guppy,
Forgetting emergencies and unusual stuff, this interested me...
No need for SOP's. We have our performance, it's well known, and any operator of the type, including British Airways, will fly the minimum speed in the climb when heavy, which is V2 + 100 knots, and always above 250 knots. As a condition of operation, we do not need to abide a 250 knot limit in the climb, and we don't. Further, the regulation doesn't require us to.
If you were flying out of LHR, where the SID says "Maximum 250KIAS below FL100 unless otherwise authorised" do you feel you should say anything to ATC before accelerating above 250kts?
ATC certainly would expect you to as the departure separations are predicated on the speed limit and I don't believe a BAW flight would accelerate without saying anything.