Once you determine the sit bone distance you must also consider the flatness or non-flatness of the saddle.
I bought a Specialized Phenom in April 2010 after having the sit test done. No one at the shop told me about flatness, etc.
A few weeks ago I bought another bike from a different shop. They did the sit test and the results were the same as in 2010 so I was about to select another Phenom for the new bike. The guy (who also does the bike fit) said the Phenom had more curve than the Specialized Toupé and recommended the latter. He was right. The Toupé is flatter and the ride is more comfortable. I'm sitting on my sit bones only. With the Phenom I can feel my sit bones and the soft tissue between the sit bones touching my saddle.