Traffic shaping in the core of a network won't scale. "enterprise" or private
networks haven't got much life left in them. (This is Nanog right?)
We use 2500 series ciscos for traffic shaping at T-1 and below, but that
isn't terribly related to nanog either.
One just has to look at exchange point data to see what
traffic volumes are like, I don't know of anything that
can switch VC near 2gbps/sec particuarlly with the flow life times
of Internet traffic.
It's much cheaper to shape/filter at the borders and overengineer the
core. It also increases usefull lifetime of hardware. (No forklift
upgrades).