Can't be sure but I reckon the felt recoil might be less if the velocity is dropped when using the 450s. That is certainly my experience with shooting 300 grainers in the 338 at lower speeds than the 250s.

Also, my .450/.400 seems to kick a lot less than the 338, despite a much heavier slug, though the energy and rifle weights are nearly the same.

Shooting a lighter bullet in a double should give less recoil, of course, because then the velocity tends to be kept down to help regulation.