I dont know where you are getting those numbers from for Antminer earnings. When I put 1.6GH/s into Coinwarz it tells me they earn $0.16/day mining the most profitable coin.
The Bitcoin side of the Gridseedx5 runs at 8G and Coinwarz makes that a profit of $0.79/day. Running it in Litecoin only mode produces $2.5/day on the best Scrypt coin according to Coinwarz.
This is very close to accurate, also there are coins much more profitable than Litecoin,
If you mine DOGE for example, and you have 10 Gridseed miners, you are making $45 a day and your ROI is 60 days and your annual return is upwards of $16k (all things remaining the same)
Your power cost for a whole year is less than $100
so why not??