1. Read my OP - "..spanning from Q650 to PM9600."

2. Flexibility and speed. Especially 10 -15 years ago. Narrow drives started dissapearing at that time and move to UW drives seemed logical. Besides, when working in enviroment where clients pay you by hour, moving large amounts of data /waiting while program writes new file to slow drive would be at client's expense and make them very unhappy.