Good idea. That may not possible in 2017. Maybe they will add in 2018. Even if they do, is it likely to be a daily train? More likely twice/thrice a week. The good part is that it may end up being faster than the Sanghamitra Express! :)
The difference in GN and 2S seems to Rs 350/- for the end-to-end ticket (510 vs 860). I had not checked this aspect earlier. Maybe if one can afford a GN ticket, paying for 2S is not a big ask after all.