This is a follow up question to Archiving web content annually. One site or sites by year?
We are completing the import of tens of thousands scientific abstracts into a single site. The most recent two years of abstracts were hosted on separate domains (conference2012.org, conference2011.org) and represents around 3,000 pages.
I have the ability to add redirects to every single document on the smaller sites and redirect to the new, main site. However, I am uncertain if Google will slap a Panda, Penguin, or Farmer penalty on the new site for receiving so many redirects from two other domains. But if I don't redirect, I'm concerned that I'll get nailed by the duplicate content penalty before the old sites de-index.
How do I set up this type of migration?