If you use more turns and larger wire then the coils will not fit the stator.  To fit the stator with more turns per coil, you will need to use thinner wire.  The longer, thinner wire will have much higher resistance.  So your maximum output will be reduced to about half.  Using the 10 foot blade you can produce more power in low winds.  But if you want high power in high winds, then the seven foot blade will actually deliver higher power without burning out, because it will have a lower internal resistance with its thicker wire.

Personally I tend to go for a larger diameter with a lower max power because that results in steadier power output, but most people prefer the idea of a high maximum power even if it is rarely actually seen due to the small diameter of the blades.

I hope you understand the trade-off.

Best wishes,