They are both good boats. I owned the P18-2 as my first cat. The main difference is the kickup centerboard on the 18-2 vs. daggerboards on the 5.5. The 18-2 can handle extra weight a little easier than the 5.5. I like the rudder system on the 5.5 a little better.

If I were you I would pick the boat that is in the best condition. Little items really add up when you buy a used boat. Make sure all the parts are there to sail it. No missing sails or booms or rudders.... If it's missing one item it's going to be a no sale because it's so expensive to replace items.

Keep One Hull Flying,
Mike Hill