Great choice - Cooper Canyon will not disappoint.
I went the Chepe route and rented 4X4; sadly the 950 was left at home.
Just a suggestion, if you don't already have a AAA international driver's license [they used to be $10.00] you may want to get one just in case you need a walk/throw-away. I didn't need it, you probably won't either but for $10.00 it's cheap insurance.
FWIW - I was warned not to venture off track in Urique and Batopilas as some people grow stuff down in the valleys. I didn't see anything or have any issues anywhere in Mexico.