I've sailed in both breathable and non-breathable foulies and can tell you there is nothing worse than keeping the rain off, but then removing your gear when you get back to the dock to find you are still soaked from your own sweat. If your going to get soaked, you might as well not bother with the foulies in the first place. All of SD- (and others) comments are spot on. the one thing I will add to them is the knee and elbow reinforcement in sailing FW gear. Most non-sailing specific gear will wear thru or rip rather quickly when used to crawl around on the decks for a while.
Don't get me wrong you can use other types of FW gear, but you may not be as comfortable and it won't last as long. Worst Marine can be a good source for FW gear when they close-out a specific brand or model which they tend to do.
hunter Legend 37 Semper Paratus
Formerly - Tartan 34C Yawl