SP10 is more suitable for installation in the engine room inside, but its price is too expensive! Even if Bitcoin prices back to $ 1000, your investment will not be fully recovered, even without considering the electricity cost.
And the price of S2 is better? It's actually more $/GH than the SP10. And with S2 you get this:
You'll need to RMA your current S2 back to bitmain and they will send a replacement out to you. Could take 2 or more weeks.
This is an ongoing issue with Bitmain in general. I too was just hit with a failed part, and the turn around on failed product WILL result in serious loss in mining payouts. There is an advantage to going with Bitmain for mining hardware, however due to their support on hardware with issues, you need to factor in as serious losses in revenue .