Feathered v unfeathered in the PC9 is a RoD difference of close to 2000 fpm. With a feathered prop you'll get a RoD of 2000fpm, unfeathered is close to 4000fpm.
The prop failed to feather on a PC9 in flight shutdown in 2011, leaving two pilots swinging under parachutes. The aircraft crashed about 1-2nm short of making it back to the airfield.