DeeCee - 1:39 am on Dec 17, 2011 (gmt 0)
Since you call it your alpha web-site, I assume that it will go away both from a user perspective and from a search engine perspective. (Except for the redirects that send users and engines to the right location.)
Hence losing juice is less of an issue, if any at all. Simply stop promoting and using the old web-site locations, and let Google and others learn over time, that all content has moved. Over time as Google rechecks the old content, the redirects will neither be necessary nor visible, and Google will forget about it all.
When Matt Cutts talks about the "cost of redirects", we are here talking about permanent redirects that users (or GoogleBot) would always see when bouncing around on your site. Like if Google kept finding links to old locations on your site, which then merely redirect to new. Kind of a small penalty for "bouncing" users around. Not the case for you, if I understand i correctly.
301 redirects are a natural thing, and how one "keep" link juice, when content moves. As long as the redirects always points to the same "new location", and old links are not weaved into the new content to be (re-)found again, it is simply part of teaching everyone where to go.
Just do not have "old" links on the new site, that merely bounces the user around to the new location.