I agree that HT link should be kept low, as close to 2000mhz as possible and I usually recommend keeping it below 2000 (1800-2000 for example).
Most tests out there agree with this philosophy on HT link. However, I just found this thread
that suggests HT link can actually lead to 300 point gains in 3Dmark06 as well as other 3dmark programs.
It should be noted that the NCSpecV81 (the author of the thread linked above):
*Is running his 965 BE at 4.6ghz
*Has two 5870s in CFX
*And 32-bit windows
This might not make a huge diffference but at those clocks he might need the extra Hypertransport Bandwidth where most would not. Also, I believe he has increased his HT voltage for stability...which could be risky for those with cheaper system boards.
Just some info for thought, hope it helps