I'm doing an interesting experiment on a handful of my WordPress blogs; this one is part of the test.
I recently removed one of the major, well-known and highly promoted SEO plugins. I've, in turn, replaced it with…nothing; I'm using the SEO functionality integrated directly with this theme.
I've maintained the exact same naming, tagging, and description methodology and have the following graph from the WordPress Stats plugin to show some early results.
Note: After about 2-weeks of testing I'll divulge the SEO plugin I was using and inform you of the results.