Anybody know how to uninstall if at some point I decide I don't want to participate?
»How do I leave the OS X Beta Seed Program? To leave the program, visit the Leave Program page and follow the instructions to remove your Apple ID and your computers from the OS X Beta Seed Program. This will stop pre-release updates from appearing in the Mac App Store on your computers.« – https://appleseed.apple.com/sp/betaprogram/faq
It won't be that different anyway. You'll get the opportunity to check for resolved bugs, and report new ones. If that doesn't interest you, there's no benefit.