I just bought a Nacra 5.2. I'm still rigging it up but I should have it on the water this weekend. I've only sailed on monohulls and H16s, so I can give you a good review after this weekend of what the Nacra newbie thought.

Newbie review: The Nacra 5.2 kicks H16 butt. Winds were forcast for around 10 knots but ended up petering out to about 5-8 knots. The Nacra accelerated about as well as the H16 but seemed to hold it's speed better between gusts. The Nacra also points WAY higher than the H16. I would lose pressure and look up at the telltales and I would be footing really hard. It took a little getting used to being able to point so high. I wasn't able to really test it's downwind potential since the wind was so light, but it was very stable on a reach. It feels much stabler than an H16 also. That could be my mind playing tricks on me though since I know it has an extra 6" of beam. We'll see how it does when the wind is at least moderate. I'm not quite ready for the heavy air test yet.
-Rob
Panama City
Nacra 5.2