Wow.. the self denial is incredible. Yes, enjoy your 4U, 400w hashing monster, lol. Size a fucking refrigerator for 66 GH/s.
Profit per day at 66 GH/s @ 400w = $190
Profit per day at 60 GH/s @ 100w = $174
Hashing monster > vaporware product.
You're talking initial gains. Double or triple the difficulty in your equation and try again..
Organofcorti already did all the math for you over a wide range of difficulties over on his blog