Ray, you make an excellent point about what convinces execs.
I guess one reason there are so many different LMSs is that there are so many different kinds of organizations. One could perhaps do an anthropological study of organizations to see what attracts them to different LMSs (I know nothing about anthropology - maybe not the right field?). Seems to me that execs who know nothing about LMSs would need to be convinced that they have the internal resources to make an open-source LMS work. If not, they are almost always going to be swayed by the argument that it's better to put all eggs in the commercial LMS basket so that they'll have someone else to blame (not their own staff) when things inevitably go wrong.
You could create a matrix: High/low confidence in capacity of self and/or staff to deal with problems vs high/low tolerance for problems within the organization.
I must say - I'm still amazed that this discussion still resonates strongly with people after almost three years. We must have hit upon something timely, or timeless, in the discussion.