i like when people say "shoot it at 100" or something along those lines, but never explain how one should be metering. i find you can pretty much stick to what is on the box if you are using a incident meter because they seem to expose for the overall light, or if you are going to be thinking of the sunny 16 rule. reflective meters, built into most cameras, tend to notice brighter things (good for slide film but not for negative), espcially if you are pointing your camera anywhere with sky in it. i am no expert myself, i just wanted to throw that out there and maybe someone can further clarify what i am saying.
that said, i really like portra, and nc is wonderful, because i personally prefer low contrast and subtle colors. if you want punchy colors, why pay so much for portra vc and not just shoot superia, or something like that?