I think ethOS only support Ethash algo or they only have limited algo supported. If you are planning to mine only ethereum you can use this OS but if you are planning to mine with different algo go for other OS like SMOS/HiveOS or just windows for more flexibility.
If you stay mining with ETH you can't make a profit or you can't reach your ROI back. GPU miners mostly mine what suggested from whattomine. But for me go for windows OS and mine Beam coin then hold.
Yeah, unfortunately, mining brings very little profit and you won't hit ROI since the difficulty will increase. If you mine new altcoins you might be able to make quite a lot. I managed to mine about $50 in a month with on a rx480
This is luck too though so it cannot be relied on and thus I cannot either recommend GPU mining, however, If you already have the equipment I say find new altcoins and go for it. You might make some nice profits and the thing is it will be daily and different coins. You never knew which may moon. As long as you can pay the electricity cost than its basically free mining.