The only problem I've seen with older FD's is a bit of rub unless adjusted very well. This is on very few FD's, in my experience, notably 7-sp Shimano going to 8-sp. I've never seen a problem with Campy, and have used an NR FD before on a 10-sp Campy drivetrain. L shifting is, after all, friction for the most part, the FD goes where you tell it.

The only problems I've seen with older cranksets is ring width and gap width. Some older rings are too wide to cleanly engage the narrower modern chains. Some older cranksets, set up with narrower modern chains, can have a gap between the rings that a narrow chain falls into. I've never seen this happen in person, but it's quite possible. I've never had a problem, though, going from 6/7 up to 9sp using the 6/7 crankset. Not sure about your setup.