IP Funnels?

Does anyone have experience with IP funnels?
http://www.bruceclay.com/seo-tech-tips/techtips.htm

A company with 7 misconfigured domain names -- 6 will be redirected to the
new main site. Two old ones with PR 6 and 5. The PR 6 will 301 to the new
main site. Should the PR 5 redirect to the PR 6 along with the rest (IP
funnel)? Or should there be 6 sites doing a 301 to the new main site?

Most or all have IBLs, and it's a legitimate redirect. All the information
from the other sites is consolidated on the new main site.