My other DH has gg fire gear, but I still prefer physical for sentries even though my gear isn't that great and I have no TnT. I can clear t6 rifts without shrines in 7-10min. (Just timed one with normal density 8min30s) I know it nothing boast about but it seems more efficient for me than using my fire.
Physical gear -http://us.battle.net/d3/en/profile/Google-1672/hero/48588878