As far as I know Coria uses Luxilon Big Banger without any kind of hybird stringing. Tennisfan4, some players prefer the feel of polys. Some like the durability. Some think (at least with the Luxilon) it gives them better spin.
I just recently tried a hybrid string job and it lasted two days. I went back to using Big Banger. I like a really stiff string bed, and I did not see any benefit of using a hybrid string job. I heard it talked about so much on these boards I just had to try it. However, it wasn't for me. If you like using gut, but don't like the cost; then that's about the only reason I see for going to a hybrid job. (or maybe if you just want to cut down on the risk of string breakage at a bad time)