hey alex, i too first did it left-hand in the crack...this way for sure feels 5.10 as all the killer knob foot holds are behind you on the slab, virtually unusable (see above picture in will's post).
To send it 5.9 way, put your right-hand in the crack and milk those chickenheads of ease.
This is more than just my opinion...friends who have done the route a bunch of times feel this is true as well.