-
It depends on the film I think.
Yea, different films behave differently, yet still -
(with colour negative film) overexposing a bit is generally a good idea, as it gives you more detailled shadows (and you don't blow highlights so quickly, as with slide film - or digital).
And yes, the pro films tend to have more latitude so a bit of underexpose is no problem, but I'd only do this if I had to.
It depends on the film I think. Portra, Fuji Pro and Ektar are all fine with a bit of underexposure and I shoot those at box speed.
Consumer films need a bit more light as the latitude isn't as good. Some like Superia 400 are awful with shadows going to mud with even a touch of underexposure. C200 strangely seems a lot better in that respect.