I dabbled with the roller process last summer using "Top Secret Coatings" TS-4 urethane-reinforced enamel (they had the best color options). Results on my test panels were impressive. When spring comes I plan to experiment with the Wagner. The process works, you just need lots of patience and the ambition to read the 200+ pages of the legendary Moparts "paint job on a budget" thread.
I recommend reading the following, then using the roller method with either Rustoleum or Brightside marine paint... The Moparts board offers the most support for these brands.
Here's one of my rolled test pieces(before polishing):
http://img.photobucket.com/albums/v4...z/100_2454.jpg
Moparts discussion board, thread I:
http://board.moparts.org/ubbthreads/...0&fpart=1&vc=1
Moparts discussion board, thread II:
http://board.moparts.org/ubbthreads/...0&fpart=1&vc=1
Moparts discussion board, thread III:
http://board.moparts.org/ubbthreads/...0&fpart=1&vc=1
Enjoy!