Over the past 6 years, I've run the gamut with my Smartboard. To start with I had a Smartboard on wheels and a projector on wheels. I very rarely used the Smartboard as anything other than a screen then because with every little movement I had to reorient the board. Sharing, while kind, is also a problem. I'm a person that gets set in a routine and I couldn't count on having the board so I stopped using it altogether.
This year I started off with a mounted board but my projector was still on wheels. As whatever mentioned, the projector has to be close to the board. My students usually sit at the carpet when we're using the Smartboard and that cart was being bumped CONSTANTLY! I teach first grade and I just I couldn't keep them away from it. There were times that I would have to stop my lesson because I was tired of reorienting. It was a big problem.
Last Friday I came in my room and they finally mounted the projector. It has been heaven since then! I orient once in the morning and that's it for the day. I don't have to worry about cords being everywhere anymore. The shadow isn't near the problem it was before.
The only other thing I'm waiting on is a step. The other primary teachers have one that runs the length of the board and it's great for the students to reach the top of the board. Even with the long pointers, my students are too short to use them effectively. I'm just waiting on it to be built.
Hope that helps give you the info you're looking for!