In my experience, TCP deals better with packet loss than a jittery RTT (caused by huge buffering capability on linecards)

Unfortunately most people writing up SLAs have RTT measured as a very long average (so a little bouncing around does not matter) but have quite low packet loss targets. So they are biased towards large buffering to achive near-zero loss. Obviously the best option is to offer different classes of service, one providing constant latency with loss if neccessary and one providing minimal loss with excessive buffering. Pete