Interactive Whiteboards or Interactive Projectors?

A question was raised this week that has played on my mind and I'd be interested in your opinions. I was supporting an ICT-Team meeting where the school were discussing (amongst other things) their budget and what they might purchase to enhance ICT in their school, when the subject of Interactive Whiteboards came up. It seems the team were not entirely happy with the boards installed throughout the school and favoured a move towards another IWB supplier. A teacher from another school who was attending the same drop-in session then asked this question - had they considered the use of Interactive Projectors as an alternative to Interactive Whiteboards?

This is an area, I have to confess, that I haven't really investigated.  My comfort zone, as I suspect is the case for many, is the use of SMART, Promethean and (to a lesser extent) RM Classboards.  I'm comfortable (there's that word again) using the majority of the functionality in the IWB software and also enjoy seeing it being used well i.e. when it enhances teaching and learning, particularly when children are able to interact with the board rather than it being the preserve of the teacher.  There is also the huge bank of pre-made lessons and resources that the major suppliers make available to teachers (much of it produced by teachers) that also adds value to the purchase of Interactive Whiteboards.

So are Interactive Projectors a viable alternative?  I had a quick look around the Internet (as one does) to see if I could find a definitive answer and although I found the odd blog post such as this that was useful, did not find much from an educators perspective.  Looking at one of the videos attached to the post (embedded below) I can see some of the attraction to Interactive Projectors.

The flexibility to project an image to any wall, screen or even floor and still have the interactivity could be a major plus point to schools where wall space is often at a premium and flexible working areas become more common.  The idea of being able to interact away from the board is also something we have been looking at for a while through slates, Apple TV, screen-sharing apps and a variety of other methods in order to move the teacher away from the traditional front of the classroom position, with varying degrees of success.  The ability to use the computer's own software rather than relying on 3rd party software to interact with the board is also a plus from a training point-of-view, but does that come at the cost of functionality?  And in this age of austerity, the cost of an Interactive Projector is attractive in comparison to the cost of purchasing Interactive Whiteboards.

This is definitely an area where I would like to do a little more research and have a better look at an Interactive Projector myself, rather than simply watching YouTube videos.  I'd also like to hear more opinions from people with a background in education.  If you could point me in the direction of any useful reading material or are an educationalist with experience in this field, I'd be very interested to hear your opinions in the comments section below.

Thanks in advance.