There is a soon to be published book edited by Sharon Senk and Denisse Thompson entitled something like "What Research Tells Us About Standards-Based Math Curricula." There is a chapter on the research of each of the NSF-funded math curricula projects K-12. (well, maybe only 75% of them, but close to all.) Following each of the sections on elementary math, middle school math, and high school math, there is a synthesis chapter and a critique of the research. The only problem is, the book is somewhat delayed. The authors of individual chapters may be of help. I can send anyone who wants it a copy of the "Investigations" research (a shorter version than the chapter), which includes results of four studies--two dissertations and two in-house studies. Hope this helps. There is research on these curricula, and as far as I know, little or none of it has been done by the publishers. Yes, some of it has been done by the developers, but the developers include top notch researchers, university professors, and other experts who are well aware of how to deal with possible sources of bias in conducting and interpreting research.