In my experience they have exactly the same wear rate, but in practice the softs last longer because they are still driveable when worn down, while the hards just become wet soap.
I noticed that too
Regarding your earlier remarks about the Cusco '08 being too fast I took the Apex and the Cusco for a couple laps at Laguna, and was at least one second faster in the Cusco.
It is not so much because of power, much more to do with handling, Apex being a tail snappy MR while the Cusco can be thrown around mercilessly and will always forgive you anyway.
But then, it might play out differently on other tracks, so I am not voting for a slower Cusco yet (at least not until saturday since I got it for friday's race

).