It's a complete toss-up. The boats are essentially equal in speed, buoyancy, pointing, and weight capacity. The small differences: Nacra must "foot" rather than point high to the wind; it doesn't matter as the lower angle is compensated by extra speed, and both boats will arrive at the weather mark (equally sailed, with equal sails) at almost the same time. I think the Nacra has a slightly higher maximum speed potential, and I KNOW it's a wetter boat - many is the time I've come in from a windy sail on my 5.O with the mainsail soaked with water up to the spreader on the mast, and without ever flipping too! Oh yeah, it's slightly more difficult to flip the 5.O.

PS: Just re-read the original post. The 5.O is definitely more resistant to pitchpoling. Altho I've never PPed either boat, I've worried more on the Prindle, and I've buried my 5.O to the main beam MANY times. Again, good luck.