Hello, thanks for your reply.

I am mostly on the supply side of the aforementioned "statistical guts," so I am not sure I am the best person to ask. The two big questions (which I am sure are obvious to you as well) are (a) language used, and (b) what functionality do you want in the "guts"? For instance Kevin Murphy's BNT has a lot of stuff, but is written in Matlab and not R. The fact that lots of people have to pay for Matlab will hinder adoption. SAMIAM is not open source, I think.