This question is so vague that it is nearly impossible to answer. I have a feeling that the basis behind it is based on large wind turbine experience.
For the average small stand alone machine with batteries the total energy capture is only a small part of the requirement. For grid tie of any sort and particularly the large stuff energy capture stands above all else.
There is very little energy in low winds and from a commercial point of view it is not worth chasing if it costs you in terms of total energy capture. If you can get it cheaply then it may pay off.
For best energy capture you need to track your prop speed to follow wind speed and you have optimum performance all the way up the range. ( Mppt)
This is a big challenge and the early grid tie machines were constant speed so they didn't have optimum performance over the whole wind speed range. Playing with prop pitch did extend things a few %.
Later ones used 2 speeds with dual alternators ( or pole change) and this kept the performance over a wider speed range. Considering that there is little energy below 12 mph and probably more than you can handle above 30 mph this was a good compromise.
The present schemes usually are fully variable speed with dc link and a form of mppt tracking. They give best results but performance is not the only reason for their adoption.
I have seen it stated somewhere that the gain from variable speed operation compared with stall operation is about 12 % but that depends how far up the wind speed range you go before shutting down. If you can keep the mppt running in higher winds then the gain may be higher.
How does this relate to small stand alone battery schemes? I really don't know. Things are very different and the individuals load usage would affect the answer a lot.
There is no question that a good mppt scheme can double or possibly triple the output at the top end ( assuming you start with the same low wind performance).
If your batteries are full and you dump the energy then you may gain nothing unless you include the heat. if you can adapt your living to use all the power on high wind days then the gain may be very considerable.
One thing that remains certain after considering all the aspects of the machine is that the thing that determines energy capture above anything else is swept area. If you want most of your energy in low winds a larger prop will do more good than any change in the loading scheme, but for a given swept area the mppt gives a dramatic potential improvement.
Probably not what you wanted but food for thought.
Flux
