Correct, Many freight from Wadi-SC run on Wag7,observed many Times, Also sometimes goods train is accompanied by Electric locs till Wadi from SUZR side with the help of EMD. I dont know about ETS but I think Loco change is tough at Wadi. Also by March-2016 Electrification between Wadi-GR will also be done, So entire Chennai-GR will be doubled and electrified.