cost of production/oz of gold

I have noticed reference to Total cost of production being a far more relevant figure than "cash cost" and agree totally. As investors we are far more interested in the ultimate monetary value.
For 2012 SLR published it's Cost of Sales for 83347 oz as being $86407 i.e.$1037/oz. The c.o.s. figure is 64% of Revenue.Q1/2013 revenue was $39m for 24286 ozs. Because costs were above normal in Q1 I used 67% as a c.o.s. percentage which gives $1076/oz.
I think c.o.s. will include more than just costs of production.
Do you guys agree with these thoughts? in which case SLR's cost of production is less than some think.