If you just want warm/dry clothing then a Mustank work suit would do the job nicely. The CG uses them here in the winter. A gumby type survival suit (the cheaper ones) are pretty much good for floating in the water for a couple of hours after your boat sinks and nothing else - IF you can get one on. I put one on at a demonstration once and it was a task on dry land. It would be really tough on a rolling boat. Once you get a gumby suit on you pretty much can't do anything except jump overboard. If I wanted a survival suit that I could put on in advance of really cold weather sailing, I would spring for an ice rescue suit. They cost about $500, but at least you can move around in one relatively easily and actually do something.