So, I found
this synopsis of a Swedish newspaper's winter tire test, which blasts the Blizzak WS-50 in favor of the Michelin X-Ice and Nokian Hakka RSi (at least for easily available tires in the US). Looking at the tires in the German test I noted earlier in the thread, the Vredestein SnowTrac 2 seems to be grouped with more performance-oriented tires rather than studless snows (although I can't tell if the Vredestein was tested in the Swedish test, unless someone can translate--links
here ) Again, to confuse things more, the newer Blizzak REVO 1 seems to be rated slightly higher (at the Tire Rack) than the WS-50, so it's possible it would have fared better in the Swedish test than the WS-50.