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.
Also, the longer tube you build the less effective the system becomes because the pressure at the top has to move the entire column of [viscous, turbulent] air down the pipe. I haven't done any math on this but I'd imagine it would not take that much height to hit a point at which point piping losses become overwhelmingly large in proportion to the energy you're producing. The turbine and the inlet need to be close together.
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.