I have 2 SP10's + 1 S2 running in my garage.  You are 100% right in that I had to re-seat each S2 hashing board before plugging it in.  But now, it works like a charm.  The S2 does draw 50% more power than do SP10's.

HOWEVER, the S2's are super-quiet.  SP10's are so loud that even if I really really wanted to, I could not add one to my collection.  Which basically, leaves me with the S2 as the only option on the market.  You cannot underestimate the value of quiet.  I can overcome the rattley stuff inside.  Noise is very difficult to overcome.