My two cents.
Coincidently around the time of Bourbon I had pulled my absolute link from my home page to my conventional sitemap.html page. This page had absolute links to virtually all pages in my site. Since I use Front Page (2000), my internal linking, other than my sitemap.html, is primarily relative. (Historically I had found the absolute links boosted my backlinks and therefore PR, that'll get an argument started!)
After I pulled the link to my sitemap.html file, my site went from fully indexed to about 20% of the pages correctly indexed, the remaining 80% being URL only (partially indexed is Google's term). Google reliably crawled all pages many times, they remained URL only! I had already done the 301 redirect and actually wondered at the time whether this caused the problem (it didn't), but my site was properly indexed anyway.
When I restored that absolute link from my home page to my sitemap.html file, my pages were reindexed in the next couple crawls. This sitemap.html file is very low in my relative internal linking structure.
Google appears to be showing a strong dislike to relative linking only fully indexing the highest level pages. And without the sitemap my linkage structure is much more hierarchical. (I was doing all this fooling around, trying to elevate my homepage PR and not waste PR on pages like my sitemap! Don't want to be HiJacked.)
Boom, I drop one critical link just as the Bourbon starts flowing!
I also have implemented sitemap.xml with priority, but I'm confident the absolute linking versus relative linking was the key. Why?
I pulled my link to my sitemap.html page again! Guess what started to happen, pages were going URL only! I still have relative internal linkage, but the sitemap.html with absolute linking is what I believe is keeping my site in the Google Index.
I'll probably go with full absolute linking, (frankly I shouldn't have to), but it may prove problematic with Front Page 2000. (FP has it's advantages)