Just found about
http://www.rigwarz.com/ My only know-how comes from the forum, but it seems that I found an
unbiased opinion about the SP30. It seems that it's doing very good besides all the trolls whining. Only 2 days ROI difference between S3 and SP30. Makes me feel warm and fuzzy inside.
Edit: Well if you add the 12 PSU cost I think that the SP30 might achieve ROI just a little faster than the S3s. Math is nice! Crypto is uber!
Sorry, but that site is significantly flawed. For instance, it claims "* Prices do not include shipping or tax.", yet the S3 price does include shipping. Furthermore, "** ROI calcs assume static conditions for ranking purposes only." It's impossible to compare miners with static conditions fairly.
Only under misleading and unrealistic comparisons might the SP31 ROI before an S3+.
Here's a better comparison not based on absurd math:
S3+ vs
SP31S3+ ROI: 180 days
SP31 ROI: 360 days
There's also a huge change that S3+'s are overclockable to ~500GH. There is also a chance that the SP31 performs like SP30 should have at ~6.6TH but I'd guess it's more likely it ends up closer to 4.5TH.
It's also worth noting that many can use an S3 as a space heater during the winter for free/cheaper electricity.