This is probably more of a personal preference. I have a Kayak style PFD and a Gul Harness with back support (as found on catsailor.com). I wear my PFD over my harness and a stretch lycra top over that to keep from catching my outhaul stopper ball on my PFD--this I learned from experience in a race <img src="http://www.catsailor.com/forums/images/graemlins/confused.gif" alt="" />.