Not often I see mountainbuzz referenced in an academic journal, but I'm catching up on the reading pile that's been building up on my desk and noticed that there's an article that did a brief sample of in-the-field shoulder relocations: Elsevier
Upshot - kayakers often have dislocations without fractures, and if you know what you're doing, relocating in the field seems safe. High impact sports (biking, skiing, climbing, etc) have more fractures, so be more carefull before pulling on stuff.
Caveats - it's a small study, and each individual patient is, you know, an individual.
My take home - take a WFR (and make your friends take one) and learn how to respond.
Safe boating out there this year!