Mary,

The F16 is, in theory, very similar in speed whether sailed sloop 2-up or uni 1-up--that's one of the neat things about the class. In reality, it is easier to sail the boat 2-up for a couple reasons: 1) Sloop is easier to tune and tack--adjustments like mast rotation and downhaul need to be more precise sailing uni, the jib helps maneuverability at during starts and tacks; 2) It is easier to manage the spinnaker sailing 2-up (2 people handling 3sails instead of 1 person handling 2 sails and trying to steer, trap, etc).

Either set up, the boat is fast and fun. I'm sure there's a lot of sailors out there who could sail faster than me with either set up. I think that despite the slight disparity with the Portsmouth and Texel ratings, racing 1-up uni vs 2-up sloop as "first across wins" would be fair and fun.