I have a huge noprocrast.
Having to /logout just to check out a story or its comments that I got linked from somewhere else (and that I know I really want to check, specifically) is really annoying.
To me, this is a completely different use-case than browsing stories on the front-page. Browsing of the front-page is a significant threat to my productivity, hence the huge noprocrast. Browsing of stories I have a direct link to is not a significant threat to my productivity.
Hence, the suggestion above.