A variety of heavy twins later saw life as turboprop twins. The two that I am most interested in are the Navajo/Cheiftain and Cheyenne and the C-421 and C-425/441 Conquest I/II.
What, if any, advantages was there to putting a turboprop on these aircraft? Were there any marked improvements in performance or dramatic reduction in operating costs? As far as I can tell from looking at aircraft.com and Trade-a-plane the Conquest I pulls a significant price advantage over Golden Eagle.
So was there really a big advantage to using the PT-6A/Garrett 331 over the big geared Continental 520 or the Lycoming 540?