Did I kill Your thread?
Sorry, I didn't mean to!
I don't think the lower tooth section in the gullet area is touching much wood during a cut due to the cutter beeing angled.
But the rivet heads do and they can create a lot of drag as the cutters get filed/ground back.
Also, I read somewhere that clipping the cutters heel helps reduce drag by letting the chips exit the cutters underside sooner.
It also helps by creating a little more chip clearance area.
The biggest in cut power loss I have noticed is caused by chip clearance issues.
This issue can be addressed in many ways, but I will not enter that debate/discussion.
I haven't truly PLAYED with chains too long.
It can be fun and educative!
If You don't try things You won't know what works best, or at least better.