Cyclob - 9:53 am on Oct 27, 2009 (gmt 0)

Hi...

I have an old site that already 301 redirects page by page to the new domain about a year ago.

Assume that all new pages of new domain had been crawled and cached by Google from the 301 redirects, should I keep the redirects still?

Or can I serve 404 to the old domain instead? If not, then how long should I keep the 301? Is it gonna cause something bad if I take 301 down and serve 404 instead?

thanks in advance for any suggestion.