The harder tungsten jig transmits energy better, which lets you “feel” the structure better. This in turn enables you to work the Drop Tg more effectively and feel underwater structure, as well as the bite.
Tungsten emits a different sound when bounced off rocks, logs and structure. While lead deadens sound, tungsten amplifies impact which can attract fish.
The heavy Drop Tgn helps keep the coil out of your line. A straighter presentation translates into more felt bites, and a better hookup ratio. This is especially important in heavy current, where you need a tight line.
And Tungsten shows up better on electronics than lead, helping you with a better bait presentation.