Our boat sits on a mooring year-round in Coral Harbor in the VI. We did the bottom paint four years ago with 3 coats of Micron 66 over two coats of primer / sealer (different colors). Between a slight current and the boat's dancing, water is constantly moving past the hull to some degree when she's not being sailed.
We saw minimal growth on the hull over the first 3 years - easily taken care of with a quick snorkel / scraper exercise once in a while. This past year, we started seeing a bit more growth (particularly along the waterline - no surprises there), and the sub-color is starting to show in a few places, perhaps 10% of the hull's surface. We will likely haul out and repaint next summer. Although the paint wasn't cheap, five years with probably 8-10 easy scrape jobs over that period seems like a pretty good deal to me.
I'd be interested to hear whether our experience is typical of what other people are seeing with their paint choices.