@Exeng, reduced climb thrust doesn't really save any engine wear and therefore maintenance cost. Reduced take off however does. At least thats what boeing tells us, not to mention our own 15 years of experience operating the NG. Therefore we reduce the take off thrust as much as possible using both fixed derates and assumed temperatures for the last 10 or so years, however once we get an unrestricted climb clearance or at airports where it is given on the ground we select unreduced climb thrust manually. It is nice to get a load of additional thrust at climb thrust reduction and climb out of the "dangerous" below 10.000ft environment in 2,5 minutes.
Anyway, over here there is no speed limit below FL100 if one is within a class C airspace.