Do you have the chance to shoot each? If not ask Dan if he has a "loaner" of each and shoot them.
To me they really shoot differently, the Whip is a tad faster, a bit more "dead" on release, and equally quiet. Mine is a bit more spine tolerant as well as the shelf is cut to or closer to center.
The Super D is the best of the D shape bows I have shot with no noticable shock, only a very, very slight and not unpleasant "thump" at the end of the stroke. For me the Super D, especially with the newer grip (he changed the grip slightly a few months ago) points a bit more natural, but thats very subjective.
Best to shoot both if at all possible if you have to choose only 1.