t-bag: Not wishing to be controversial but in my experience (737, 747, A320, 787) they all behave pretty much the same in the descent. Sure, the FMC/FMGC and autopilot behaviour may vary but aerodynamically they are all heavy, swept-wing jets; they will go down or slow down, but not at the same time.
Whether 250KIAS in the descent is achievable at e.g.FL350 is another question. IIRC, all except the 747 should be capable of it.
If the FMC/FMGC speed schedule is preventing or delaying compliance with an ATC request, you can always use 'FLCH' or 'Open Descent'. That way you can control the speed manually.