John, I can not express enough how much much I use them for so many different reasons. But to answer your question simply, its much more often than the 2D.
Now, like any other technology, it is really a matter of what is YOUR expectations are, and if YOU will actually use it.
Just an example – You follow a contour line around a rock bar that is in a river. The turbulence that will normally garbage up your screen in 2D is much more clear in the DI. In addition, you can clearly see the rocks that protrude out like fingers that create the spot-on-spot locations.
I’m sure that most can guess what the pic is. But anyways, at the end of a short wall, the turbulence was too much for my 2D and I wanted to see more specifically where walleyes were hanging at as we made a couple drifts down. I motor’d up with the SI and was able to pin-point a few square foot area that was holding fish. Technology is there and performs to nearly any level in which someone is going to use it.