In alot of those tests they compare an old low rated studded tire against modern studdless tires. You can get modern design snow tires that can be studded and have the best of both designs.
The General Altimax Arctic is highly rated without studs
http://www.consumersearch.com/snow-tires
The Tirerack tested it with and without studs and found it better on ice with studs
http://www.tirerack.com/tires/tests/testDisplay.jsp?ttid=123
My 2wd open diff Ranger with General Altimax Arctic studded tires works much better on Ice than my previous front wheel drive 4 cylinder car did with Bridgestone Blizzak WS50 tires.