Very complex aircraft, with complex systems. Knowing how to recognize failures of the systems and what to do about them when they fail is very important. A lot of this stuff is not covered well in the POH. These planes are docile and extremely forgiving, but have corners where they will predictably bite. Would a highly experienced, non-PA46 pilot know where the unmarked drain holes are for the rudder cables and what can happen if they are blocked? Know the credit card test (not in the POH) to ensure the steering rollers are adjusted correctly? Know the accident history of the aircraft such that every conceivable scenario that has resulted in a mishap or death is in their database while training you? There are numerous PA46 instructors with over 10,000 hrs in PA46's. There has never been a training fatality in the PA46. For an airplane that every single aircraft requires at least yearly training, that is an astonishing record. The known PA46 specific instructors are very good. Don't skimp on the training with these birds. If for no other reason, you are leaving a lot of tribal knowledge on the table going to a non-specific instructor.
I have studies the PA46 accident record extensively. It reads like a cheap novel of almost exclusively preventable accidents. Probably not that different from a lot of airframes, but so sad that poorly trained and poorly qualified pilots have given such an incredible airframe an average accident record. With the capability and redundancy of this aircraft, accidents should be way fewer than average.