So when JR produced his own at school and gave me a demo, I was really interested in seeing how it would work (and impressed about how he had put this together - he assures me that it was not a long process).
This photo shows the remote dangling below the ceiling-mounted projector. It connects blue-toothly to the computer and the infra-red detector detects the special pen - here is a schematic diagram from Jonny Lee's site:
It worked really well. As long as the presenter's body did not shield the remote from receiving the infra-red signal, then it seemed as responsive as a "normal" electronic whiteboard.
JR reckons that it would cost sub $100 including the software. Seems a very good alternative.
I wonder whether its positioning can be improved? Short-throw digital projectors are the vogue so I wonder if the remote could also be placed much "shorter-throw".
We are also going to experiment with the Mimio bar - this also retro-fits on a normal whiteboard. BUT, having seen this adaptation, why is it that the Mimio system and similar others are SO EXPENSIVE? Surely they do not need to be - common manufacturers!