I've posted this before and had a chance to do some durability testing with an 8 single (stop go, brake, stop, go, brake). So far it has held up well. Make sure to use blue-loctite on the set screw or else it may loosen up on you....

This is Beale's idea and utilizes a secondary non-one-way pulley that has the boss machined/lathed off. It was then lined up and had two holes drilled. Finally it is held together with two rolled pins that were pressed in with a lot of pressure.

Exploded view of locked center pulley concept by Beale