It does, but the small gain comes at a cost, namely your time and a weaker blade. My argument is that making the investment in a blade with the correct twist down to the root and proper management of drag is likely to give a greater increase in efficiency. Can anyone demonstrate the actual benefit from using cambered blades? I suspect to do that would require wind tunnel tests, which are beyond the scope of most users of this site. I have not seen such data. The situation is further complicated by the fact that a 10% increase in wind speed results in a 33% increase in available power, and it is virtually impossible to measure wind speeds accurately in the field. So, again wind tunnel tests are required.
As far as the tip vortices are concerned, don't slough them off lightly. I recently saw a few seconds of video on the tube showing a curtain of smoke moving downwards. A model plane was dragged through it. The result was two beautiful large vortices that slowly moved down with the smoke. They seemed to extend halfway or more down the wing. Unfortunately the whole thing happened quite quickly and no dimensions were given. Well, it is well known that the tip vortices reduce lift in an airplane wing. The vortices occur at or near the tip where everyone claims the greatest power output is achieved. Well, maybe, in fact, the blade is really putting out maximum power from half its radius to three quarters of its radius. I have suggested in the past that the way to ascertain the true effects of the tip vortices would be to test the windmill in a circular wind tunnel having a diameter only slightly greater than that of the windmill.
So, my advice has been and will continue to be that unless you have the knowledge and access to a wind tunnel, don't concern yourself with complications to blade design above what you see here. A slight increase in wind speed will more than make up for any increase in efficiency.
