Fellow blogger and integral enthusiast coolmel alerted me to an ongoing war between Cowan and Wilber -- mostly it's Cowan hating on Wilber/Beck. Cowan has hurt his argument by descending to name-calling, but he raises some valid points before doing so.
Here are links to the relevant articles. I leave it to the reader to form an opinion based on evidence and personal experience.
"The Missing Links" of Spiral Dynamics and Ken Wilber: The Mean Orange Meme (MOM)and the Healthy Green Meme (HGM) by Bill Moyer
Wilber's reply: On the mean memes in general: Red to blue to orange to green to yellow by Ken Wilber
Cowan's reply to Wilber: Response to Ken Wilber's Response to "The Missing Links" of Spiral Dynamics and Ken Wilber, a posting by Bill Moyer on the Post-Conventional Politics (Post-Con Pol) discussion list, reproduced on The World of Ken Wilber website by Chris Cowan
For additional rejection from Cowan's camp of the Beck/Wilber work, see The Mean Green Hypothesis: Fact or Fiction? by Dr. Natasha Todorovic.