I just finished up painting the decks of my boat with Interlux Perfection and I'm pleased with the results. The gloss is incredible and the finish is really hard. From what I've read on the product, you can expect it to hold up for several years at least. I went with Perfection because it is touted as a 'do-it-yourself' finish and is intended for the roll and tip method (as opposed to spray). I believe several other paint manufacturers offer similar products but I have no experience with them. I also did my sailing dinghy with the same product and it has held up well dragging it over sand since I did it last month.
Based on my experience, I'd say 90% of time spent on the project was on surface prep and priming; the final painting part was easy, but these 2 part paints hide no sins. If you have any imperfection on the underlying surface, the glossy paint will not cover it and will actually highlight it and make it look worse (it will be shiny though).
I recently wrote up my thoughts on Perfection here