There are lots of people that can teach you to use the equipment, once you have made the purchase. You use a machined, registered fit to insure the alignment. A simple method to use. Not too good a method if there is axial float from sleeve or journal bearings. Given a choice I would select the C or D frame every time.
Automotive people use the same concept to align an automobile transmission to the engine.
The concept was originally developed for the marine industry where it would be impossible to bolt the motor and pump to the deck of the ship, and then do an alignment. The hull flexes making any conventional alignment ineffective. The same logic applies to off shore drilling rigs. The adapter does a better job of equalizing the heat transfer between the pump and the driver. It does not all have to conduct through the shaft.