JISC - the body that funds provision and support of ICT for UK education and research - has published a much anticipated report on the economic impact of alternative scholarly publishing models. The lead author, John Houghton, was also involved in a contoversial study on research communication costs in Australia published in September 2006.
I am afraid that I have not yet read the whole report, but:
Any study of this type depends heavily on the assumptions that the authors' make (these assumptions are very helpfully listed towards the end of the report). Many of the assumptions are based on 'industry consultation' and yet none of the major trade associations nor the major publishers (as far as I am aware; I am trying to verify this) have been consulted. Several of these assumptions are, IMHO, highly questionable although in fairness I have not yet been able to work out the impact on the headline numbers. More still are 'authors' estimates'. These seem to have no evidential basis at all and some of them appear to have a very direct impact on the headline numbers.
It doesn't inspire much confidence so far, but as I say I haven't had the chance to read and digest all 288 pages yet...