The Hy6 + 6x6, for me, is very well worth it. "Full frame" capability in an autofocus medium format camera means I now have the ability to take semi-action shots of my little kids as they run around, without needing to use the magnifier on the finder. I generally trust that the focus is accurate, and so far I haven't been too disappointed. I like that I can now focus on just composing the shot in the WLF, and rely on the electronics in the camera to do the rest of the work. And, when I want to be more contemplative and deliberate about getting a scene just right, the camera has that capability too.
Really just all around the best camera system I've ever owned, film or digital.