Campy crank compatibility: 9 vs 10

[bcm119]

I was looking at Branford's website and they recommend using "Le Tour" 0.4mm spacers to use a 10 speed Campy crank with a 9 speed drivetrain. Apparently the 10 speed big rings are 0.4mm closer to the little ring. Is this really necessary? 0.4mm seems awfully small to make a difference. I run Campy cranks with a Shimano drivetrain anyway, so I'm not a big believer in strict compatibility rules. Any experiences?

[pale scotsman]

I ran campy 10 speed cranks on a campy 8 speed drivetrain and found no issues. The same old chatter when you are running small to small and the next cog up, which you shouldn't do anyway. Try it out and see. Me thinks .4mm ain't squat too.