[chef] Chef Server vs Chef Solo and MCollective

[bradford < >]

I have 6 rails applications, with various databases on multiple
servers (2-4 per app).  I'm evaluating Chef right now, and will be
honestly that I haven't gotten very far yet.  While researching, I
came across a slide[1] that suggested Chef Solo + MCollective over
Chef Server.  The slide basically suggest that Chef Server is
complicated, not well suited for multiple environments, and not as
well suited for multiple projects and to use Chef Solo + MCollective
instead.  As I said, I'm new to Chef and am looking for (1) further
explanation into these claims and (2) recommendations on which to use.

[1] 
http://www.slideshare.net/jweiss/build-your-own-clouds-with-chef-and-mcollective
(slide 25/61)