Do you think the lighter reciprocating weight reduces the stock blocks susceptibility to cap walk?

I'm pretty sure it's "yes", but is it significant? IDK.

What I don't understand: we KNOW the crank manufacturers understand windage, pumping loss, and aero shapes at that speed in f/s. If they don't, the volume of information available is huge.
Assume they don't want to change the shape of their basic product on the shelf.
Why not offer directional profiling as a post-manufacture operation with a high markup? Even 2 hours of shop time with a grinding wheel (not a head porter or master machinist, just an adult) contoured to do only the nose is an improvement. Position it, feed in until the improved shape appears, back up, dil over to the next.
Remember, the bow wave and trailing wake are resistance (uses power to heat up the oil and crankcase vapor) regardless of power output - it's there with the spark off.