I also have a Crewsaver Ergofit, but the 190 Coastal, Hammer Activation. Love it! Very comfortable! Feature packed!
the Adventure Safety site has some good info on PFDs
http://www.adventuresafety.com.au/news/Here's as an interesting video on cutters, which I think are a must have when tethered. A cutter is a safe way to cut yourself free without worrying about puncturing the PFD (or stabbing yourself) as when swinging an open knife blade about. It's the most under appreciated piece of safety equipment you can find for $30.
www.facebook.com/adventuresafety/videos/1078064208894756/whatever PFD you buy, the first thing you should do is download the self service guide and see how it all works, put it on and manually inflate and deflate so you know to do it, where all the bits are and roughly (on land) what it is going to feel like.