Here`s my non-scientific view on the subject :
Where I sail we sometimes have to race in less than ideal catamaran conditions - All sailors are on the same boats (Dart 18), some sail double-handed, some single handed in which case they remove the jib and are fairly similar in speed.
The single guys tend to trapeze off the leeward side in light breeze on the downwind leg, and can sail dead downwind at the same speed as the double-handed guys, but the double-handers can`t do this with the same effect - the jib gets blanketed by the main & you are effectively sailing 2up with only a mainsail working on the downwind legs.
What this translates into is that the solo sailors cream the light wind races, while the 2up guys have to wait for 10knots of wind before we can win races. Very frustrating. I`m not sure what makes it work, but I know that it does ! Nobody tries it upwind (yet), probably due to the teabag effect explained in the last post ! Having said that I have seen a few capsizes in 3 knots.
Very entertaining, since most of the solo guys aren`t heavy enough to right the boat.
I have no idea what makes the solo boats run faster than they reach, other than lower wetted surface area. I do know that it looks silly. We probably shouldn`t go racing in these conditions anyway !

Cheers
Steve