Just speculating on a technical point (rather than the noise issue itself)... Although the SIDs are all 5000, there ARE NPRs off the 24s that terminate at 3000 (right?). This is not to say that the noise abatement procedures calling for 500 fpm or greater are not relevant. Hell, it's not really to say anything except that the SIDs show 5000 but some NPRs within those SIDs terminate at 3000, and this might lead the casual reader observing from the ground to believe that all bets are off once the aircraft is out of 3, even though this is not really the case...
So help me, do NOT flame me when I'm being charitable!
Dave