Paul
The Spyder would be able to do this very easily. Inserting the cameras onto the individual monitors is easy to do and you could even produce one video source to be stretched across all displays without need of a multi channel sync playout solution.
As mentioned by the other respondent you could use a matrix switcher to hit the budget but the switch would not be seamless and all the sources would have to be converted to a format common to all the display devices. This ends up being a lot of processing gear to get everyone talking the same language and can start adding up.
As far as operation or training it wouldn’t be too bad. The Spyder allows you to write a script of moves and you can have a student follow along with the director and advance the script on his cue by simoply pressing the space bar.
Downside… Spyder’s can be expensive to rent but it would be a 1 box solution to your problem.
Let me know if you’re interested in persuing this further.. it just so happens that I own 2 Spyders
-Matt