If I look at http://sheerwind.com/technology/field-data it seems to me the 600% improvement is highly deceptive: that huge funnel tower gives up to 600% (average 300%) more output than the same tiny turbine inside it when it's just placed on top of a pole.

If you want to use this technology to boost the output of a modern 100m diameter turbine by 300%, you'd need to build a funnel tower that's over 1km high. I kinda doubt that's cheapter than building three of those turbines.