I seem to always see this theme when comparing PC2700 to PC2100:
PC2700 @ 333 but with asyncronous FSB (133/266) is 2.5% gain
PC2700 @ 333 syncronous FSB (166/333) is 5% gain
is it that too little? Are these comparisons strictly related to Athlon CPUs (since they're designed for 133... even after you unlock them?)
--> is curious

(also thought I'd post that so you had some reference)
Considering how ATA speed vs spec scales with hard drives, I'd say it could very well be correct...
honestly I don't know why I bought PC2700 for my asyncronous setup...I can only hope that 333fsb helps significantly, if not...it still isn't worthwhile. 400 should be, however.