A factor of 2x+ speedup isn't "not much to be gained", but the point again is just to be more rigorous about the security margins we're trying to get.

Can you say more about what you believe the "debate" about key size and number of rounds to be? A pretty important point Aumasson seems to be trying to make here is that the reduced-round analytic results against ciphers are arguments in favor of their fundamental strength, not signs that they're teetering on a precipice of insecurity.