'havoc, don't just go out and "double" your change interval -- do a UOA first and see how your current oil is doing, and then, if you still want to go to Amsoil's MCF 10W-40, do so.
I posted a motorcycle UOA on the MCF 10W-40 some time back -- 5,000 miles, and still in grade. That was in a Honda ST1300.
Would the MCF go 10,000 miles without shearing? You're welcome to try, especially with summer heat coming on. There is no way I would push a wet-clutch oil bath that far, though.
Amsoil's older "AMx" series bike oils are NOT the same as their newer "MCx" products. If you want the best, stick with the later stuff.