I have experimented with making all-proph calls on and off. They are certainly capable of producing some good sounds, especially low-volume calls. To me, however, they are just a bit too finicky in terms of reed fatigue, longevity, and general upkeep to keep them performing well. I prefer to use a combination of .003 and .004 and proph, rather than straight proph material. The thicker material just seems to hold up better for me, while producing as good or better sound quality.