RATE-Limiting and

Excellent point. It does depend on the traffic type.
Though I don't like to complicated my configs, you can always use CAR (cisco rate limiting) through an ACL to protect against the file transfer from the core servers issue you referred to below. It can make sure a high bandwidth xfer won't suck up all your available B/W.

Does anyone out there know how to limit B/W based on Flow or individual sessions? Or even just source (where source is random). For example, a CAR where each IP source gets no more than X% of B/W (still allowing bursts if bandwidth is available). I think some QOS tagging and queuing would have to be involved.