I have found (albeit not with the same fork) that softer on the fork does feel the same both ends – ie if I go with the same sag front and back either the fork feels to springy or the back feel too squishy.
If there is more rebound available then use it – most forks seem to work better with the rebound set on the slow side.
Good comments about the platform – presumably the fork is designed to be used with that feature activated. With the platform compression damping turned on you could get away with even less pressure in the fork, which will restore the range of rebound damping (less spring = less rebound damping needed).