4) if the s-2 fails you are at zero hash
5) if 1 s-3 fails you are at 1th hash.
This.
The above is why I only purchased s-1's
I purchased 16 had 1 fail had it replaced a bit too slowly and I was helped by minersource.net for the rma not by sushi-review i purchased it from sushi-review.
I have 3 s-1's mining right now sold the other 13. I never put any 1th machines in house.
But I am getting 1 s-3 and 1 rk-box to compare them.. My guess is I will end up with more s-3's then rk-boxes but I will wait and see.