I'll echo what @vtmecheng said. I justbought a used dual boot setup and got it installed last week. It takes a little elbow grease modifying the boots I have (radar carbitex). Standing on the back of the boat it feels like there is more play, but I don't notice it while skiing and skied right up to my personal best my first set (3@ 28off, 34mph) and have 4 sets on it now. I'm not sure I 'needed' it, but I had some extra cash this spring and figured if it saves me a trip to the ER, its paid for itself.
I had one fall where I thought it would have been nice for it to release since I tweaked my ankle slightly, but reviewing the video after it didn't seem all that bad, just hit my back on the water :)