I found this out the hard way. Changing the Permalinks on your site will kill every share, every like, every tweet, every +1... basically trashing everything you're working towards in terms of building in social cues for Google Page Rank, and promoting your content. Frustrating as hell.
Would be great if there was a simple check-box option that shows up right after install and activation:
"Data Always Follows Posts after Permalink Change"