Here's a catamaran advantage you may not have thought of: the possibility of doing a bottom job (one hull at at time) while the boat is still in the water. This is a photo of circumnavigator, Rory McDougall's famed Tiki 21, Cookie, with one hull lifted for just that purpose. (Click on the photo for a larger version, so you can really see how it's done.)
Rory brought the Tiki 21 alongside a much larger catamaran that he was watching for a friend, and using the big boat's halyards connected to the beams of the Wharram cat, he was able to hoist the hull high and dry enough to prep and paint the bottom.
This could be done in a lot of other ways as well, such as taking a line from the mast to a strong anchor point ashore, or using trees in a quiet, protected creek or bayou in the woods. One Hinemoa owner I know used to paint his bottoms at his own dock by hoisting the whole front end of the boat onto the dock one day, then reversing it the next day to do the sterns. This flexibility is one reason I chose a simple Wharram Tiki 26 to build for my own cruising. The ability to effect maintenance and repairs in remote, out the way places without paying yard fees is unmatched.