Unfortunately I dont have the answer you are looking for, but I have been in the litecoin community since the GPU days, and what I do know is that litecoin has consistently been the most stable and profitable coin in all of crypto currencies. Other altcoins and have come and gone, they go through their spikes and dumps, and litecoin has always stayed in the sidelines returning the same profit day in/out.

Like others have mentioned its definitely the long game with litecoin. Yea you can be more profitable putting your money elsewhere right now, but in the long run I have made more gains with litecoin than any other crypto. The second main reason is im constrained by power capacity (have about 10kw dedicated to mining), and currently the L3 cant be matched by any other form of hardware in terms of $mined/watt, be it asic or GPU.

For example and S9 can put out 19 cents of revenue per month per watt, the most profitable GPU algo (zcash currently) 28 cents per watt, and the L3 is now at 34 cents per watt.

So you can see where the true value of scrypt mining lies...for the home miner that is constrained by power (both capacity and price), it cannot be beat. This is the reason I have always been a proponet of scrypt/litecoin for home miners (and is the reason I started my whole scrypt USB stick project...which I hope to continue with a new version on the current generation of scrypt asics). Of course all this comes with a trade off and thats with a higher upfront cost, which again is not for everyone.

So it again it comes down to your individual needs...are you a huge farm with massive capacity and low electricity price? Go with a Bitcoin miner...do you want quick ROI and high resell value go with GPU algos...are you a home miner with high electricity and want to play the long game? Go with L3. But dont make a decision based on a simple ROI calculator and do your research.