With BTC at $286 right now - UMISOO is paying an estimated 0.74155560972143600% daily... 
Very nice, but how much power is UMISOO...? I can only seem to buy it on the market under Hash
I'm not sure I understand your question. Yes, UMISOO is available from HashNest. Choose the menu item "hash", then "UMISOO", then "market" to find the buying menu.
"Power" would be 0.67478569276522800% daily at present...
Sorry for the confusion. A hopefully better way of expressing it would be: How many GHS does UMISOO has, given that it can be bought as an unit (as we can buy an S5).
UMISOO are shares of AntS2 units. You can buy as little as 1 GH/s.
Thank you, but that makes it even more confusing. Why are UMISOO shares separated from the regular S2s, which you also can buy as little as 1 GH/s of?
UMISOO is a 3rd party datacenter that hosts AntS2 units. They were the first available per GH/s shares for sale when HashNest originally went live.
AntS2 units as listed now are hosted by BitMain. There is no difference between the two except for price. They both have the same payout and the same maintenance fee.
Why is there a price difference? I guess more people trust the "AntS2 hosted by BitMain" idea and are willing to pay quite a bit more for that alone.
Personally I am loading up on UMISOO at the moment...
No one is buying S2 contracts. Price is more expensive than UMISOO and volume is very thin. I agree that UMISOO is the highest yielding contract at Hashnest this week. It has the second highest trading volume after S5 (which has a lower yield than UMISOO this week.)