@Unacceptable makes 2 good points about Gridseed ASICs - they are much more power efficient than GPUs which keeps your running costs down, but you are limited to Scrypt based coins. The latter may become more of an issue when KNCminer actually start shipping their Titan Scrypt ASICs (apparently expected Aug-Sept now), I expect a lot of altcoins will move to alternative algos just leaving the more established ones like LTC & DOGE. Which wont be a massive problem, LTC mining will likely still be a much better ROI than BTC, but already the multipools which offer the best returns are those which focus on the "alternative" altcoins.
This post from Suchmoon
https://bitcointalk.org/index.php?topic=514242.0 is well worth viewing to give you an idea of how the returns compare (and fluctuate). Personally I have a R9 270X and two Gridseeds running, which should have paid for themselves by the start of July, but rather than purchase more hardware myself I invested the btc at Scrypt.cc - after a couple of weeks trying them out I'm convinced enough to put their referral link in my signature.
If I am not mistaking, the way scrypt.cc works is that you invest Bitcoins into their mining system and they will start mining for you and then you will get a profit back. I just want to check if that is the way it works. And also as you have been investing into Scrypt.cc, could you tell me what you think about it and if the return is really what they say on their home page.
Thank you.
EDITED: Aslo, does the KnCMiner Titan actually mine at 300Mh/s or 300 000kh/s? And will it? Because it seems to be really cheap to be mining at that speed... If my calculations are correct, if you would be mining Dogecoins with the Titan, you would be mining about 60736 dogecoins every hour or about 30$... Witch would mean, about $20,600 a month if it is on 20/7...