goodroi - 9:38 pm on Mar 14, 2011 (gmt 0)
The vast majority of link juice will be passed on to the new site when using a 301 redirect. Be careful that you do not have redirects pointing to redirects. Those redundant redirects will greatly decrease if not totally kill the link juice that is passed.
As youfoundjake mentioned Matt Cutts did say & later confirmed there is some loss with redirects so don't use them unless you have to.
It sounds like you are using the right solution for the right situation.