This story (CHT Tom Knapp) is a bit old, but I found this passage inteesting:
A 1993 survey of 188 companies conducted by the Washington State Office of Trade and Economic Development found that employee-owned firms grew no faster than conventional companies unless they gave workers a voice in management. Likewise, broader sharing of information and authority with workers didn’t boost growth unless that was combined with ownership. But firms that put the three together grew about 12% faster than their competitors.
Does anyone know if there’ve been follow-up studies?