Yes, if you were starting from scratch the ROI would probably be a year or more but everyone's situation is different.  My current hardware paid for itself in July so if I sell my 20 S5s for something like $300 each I would have $6000 towards 5 S7s.  That would make my initial investment about $3500 with 24,300 GH/s, 6050 Watts, and power at 0.10.  If you plug those numbers in it shows 94 days to break even.  Even if difficulty made a huge jump in the next 3 months it would look like maybe 188 days to break even for me.  Like I said, everyone's situation is different.