I had a 20 ft. Nautica cat and enjoyed it very much, extremely stable and fast, it porpoised a bit more than a v- hull but at rest the boat was like a rock, it pitched very little in waves. The boat also had a extremely shallow draft, you could pull it up to within a foot or two of shore, that was nice for the kids. A link to Nautica's 28 cat, a really nice boat..
http://www.nauticaintl.com/New2005/B...0s721pic2a.jpg