I have sailed a Nacra 5.0 12 years. It was a fun boat and at that time you sailed (depending on conditions) as fast as a Hobie 16. Now with the new rig (as I don't think anything else has changed) it easily sails faster then a Hobie 16.

But they are way our of league for the F16. They are nowhere near in performance, they don't have a lot of trim possibilities making the windrange to sail the boat in smaller and single handed definately more difficult to sail then the F16.
But cheaper then an F16 and a great boat to come into contact with catamaran and spinnaker sailing.

Gill