I once dove Molokini backwall with Scuba Shack. They were good dives.
You should note that several other operators also use Kihei boat ramp, including Ed Robinson, B&B Scuba, and Mike Severn. My dive club is likely do charter a boat for a backwall dive June 24, just before your arrival. We will be using Maui Diamond, which departs from Ma’alaea Harbor.