I haven't heard of the KeyWest killing stators. I'm not sure why that would be. I believe the design is superior to the original Rotax unit, but it's still a shunt regulator and will waste power for no useful purpose.

When I did have the Rotax regulator it was mounted on the cabin side of the firewall on a big heatsink with thermal compound and all.

Do you know what your normal running current draw is? I tried to minimize mine by installing LED lighting which helped a great deal. Also, the motorcycle type MOSFET regulator I'm using burns less power and regulates better than the original Rotax without the load resistor.