According to Sturgess and Gortz (pg. 1514) it was the Prussian Ministry of War that made the decision to discontinue the production of the truncated cone bullet. Again according to Sturgess and Gortz the bullet had been successfully tested in 1904 for it's "better wounding capability".

It wasn't a discussion of which bullet had the better wounding capability, but why the Germans switched to the round nose bullet.