" Any particular reason to flip the normals?"

Depends on whether they've set correctly in C4D.
I usually find it's easier to just do when importing into Poser.
Sometimes this causes a small number of faces to be wrong, but this is best fixed inside C4D with it's "Align Normals" or "Reverse Normals" rather than using Poser's "Make polygon normals consistent" or the Group editor, YMMV.