I don't know. That's a tricky question! Other example of Insight users can be see here:
http://www.gnutellaforums.com/showth...threadid=32604

http://www.gnutellaforums.com/showth...threadid=33513

http://www.gnutellaforums.com/search...der=descending

It might have something to do with the way Sandvine works I don't know! I mean if a proxy works then it's not a total block.