thx I've not done so much research on Litecoin so far, because I was not interested. But why you compare GPU mined coins with ASIC mined coins and not Litecoin with Ethereum. You compare Bitcoin THz with Litecoin GHz why not compare Ethereum THz with Litecoin?
Because they are for different algorithms. If everyone in the world with an ETH mining rig switched over to mine Litecoin right now, the power of all their machines together would not even reach 25% hash power for Scrypt. This is why it is not economically viable to mine Litecoin with GPUs.
If it was, everyone would be doing it, including me, but it isn't.