Is a MTB tire the fastest and best tire for Gravel racing?

No.

In my mind it’s rather complicated as the CdA (aero) value gets shifted some on front sus bikes only off road.

My plan is to try this on a Blur with Flight Attendant soon.

Funny enough I had some of the same Pirelli mtb tires used in Marc’s testing waiting on my porch yesterday. Drum tests I’ve seen on them are atrocious though.