For a 16hp and nominal weight penalty, Emira V6 BE saves $13k from a base Evora GT. That cost is easily the 50-100hp+ difference within Cayman or Mustang trim levels. BE is mathematically a better performance value than a base Evora GT gaining better build quality and wider track for the weight penalty and better styling for free.
Re: Emira v Cayman v C8, it's rock-paper-scissors where, to me, C8 and Emira are both scissors and Cayman is the paper.