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This is true. The rewrites using [R=301,L] are great when it is necessary to use a regex to perform the 301's with fewer entries in your .htaccess

Exactly. We were using what amounted to computer generated mad-libs to turn out a high volume of content. Panda came along and killed 1/3 of our traffic. We were also sent us a warning that we would be delisted.

Well crap. Thanks for the confirmation.

Similar to Michael, my IT team is saying Googlebot is causing performance issues - specifically during peak hours.   It was suggested that we consider using apache re-write rules to serve Googlebot a 503 during our peak hours to limit the impact.  I found the stackoverflow thread (link below) in which John Muller seems to suggest this approach, but has anyone tried this? http://stackoverflow.com/questions/4730376/how-to-set-robots-txt-or-apache-to-allow-crawlers-only-at-certain-hours