We have the opportunity to install an Interactive Technologies FP580 [ATM we only have Promethean boards]

Is anyone using Interactive Technologies? What do you/your staff think of them?

I understand you can use a pen or finger to guide the cursor around the screen/draw etc. Can you write on the board with non-permanent marker [strongly here discouraged with Promethean as the marks never seem to fully come clean and I am sure that I recall that Promethean said that we should not try it even though we get a member of staff doing t every so often]

I am interested in trying alternatives to Promethean: We have been using them for around 4 years now and I have never been entirely happy with them.

Just looking for ideas/comments really.