I’ve read a lot of posts on this topic; however, little if any attention has been placed on the difference the type of bike makes on wheel choice.
The particular example I am referring to is the difference in aerodynamics of these wheels with respect to the cut out on the P3, P3SL, P3C. I would imaging that the cut out with these bikes would greatly limit any difference that the HED 3 vs. Disc might have.
The only thing Ive seen in this respect is the distance from the chainstays from the surface of the disc. A flat disc is faster (per Zipp) when there are chainstays, since this increases the distance from the stay to the disc surface. A HED disc is better for a bike that has no chain stays (beam bike), since it is lenticular.
Didn’t answer your question though, did it? sorry!