Two summers ago I was put on my Versa-board.
http://liquidlogickayaks.com/versa.cfm
It was a windy day and I fell off the board. I wasn't wearing a PFD. As it was, I fell off in a rocky, shoal area behind a small island that sits in front of my house. Family and friends could see the paddleboard floating/sailing down the bay, and had no idea that I was safely standing on a rock.
They were scared initially...concerned for my safety. I never go out now without a PFD and I don't allow guests to use the board without a PFD.