deadsea - 11:33 am on Dec 7, 2012 (gmt 0)
I would keep up with the 301 redirects. We had a site where we changed every single url on the site in 2002. 10 years later Googlebot was still crawling the old style urls and we were still serving 301 redirects for them. Googlebot never seems to forget these things. But it didn't seem to hurt our SEO efforts either.