No way A4's ROI in a year. Given diff rises you will be lucky to ROI in two years.
Here is my math for one unit (~140 MH/s) bought at Aliexpress and with my electricity price:
Not too bad. But diff going up by 10% in the next 3 days. Who knows what it will be in the next two months. If you double the diff to 140,000 and put LTC price at $3.00 USD then run your calculator, you will see that 2 year ROI.
You must at least estimate future difficulty increases to get some realistic ROI.
As you can see LTC, is again skyrocketing due to the recent price increase.
Here's a sample assuming LTC is difficulty is growing 0.5% per period (very conservative). I used your 140MH/520W/0.04c/KwH and yielded a different result with difficulty growing. It can definitely be improved by profit switching.
http://www.vnbitcoin.org/detailcalculationltc.php?name=LiteCoin_Mining_Rig&startdate=2016-12-28&costperunit=1180&wattperhour=520&gigahazarate=140000&daytoincrease=3&testlopfirst=3&diffincrement=.5&bitcoinperdollar=4.3&electriccostinput=.04&begindifflevel=70628
