I completely agree, that a high end wheelset are not the A+ priority in making you faster.
A ton of things should go before that. But with the topic being about wheels, I think it’s appropriate to leave it at wheels.
Just to contribute my two cents:
The 4.5 are a great set of wheels. Light, stable, aero, versatile. As windwarrior pointed out, the Roval Rapide are in the same breath. Minimally higher weight, THE most stable wheels you can get, hooked design (this can be a plus or not relevant to you), and actually super aero. I just tested the Roval Rapide front wheel in silverstone windtunnel, and let me just say, they are RAPID(e)!
The 6.7 are definitely the way to go, if the courses are more flat and rolling. They are the faster wheel, but might be a handful on fast and windy descents. Also, they are narrower, so their aero shape will be best suited to a 25/26, rather than a 28 (which works great on a 4.5).
I have a set of 6.7 waiting to be set up, and will report back, once I tried them.
They are extra super bling