Obvious noob q:
My first CX season last year I rodea series of 6 races, 3 of them 45+ , 3 of them Cat 4, mostly out of ignorance as to what category I should be riding. (ACA here in CO does not have a 45+ Cat 4 for CX...not sure if that's the same everywhere).
I wound up with about the same finish position for all races, starting at the bottom and eventually finishing mid-pack.
The more I've learned, the more I think I should I ride Cat 4 exclusively this season. Yes, I have visions of grandeur.