The value of the coin would be determined by fair market value. Fair market value would be determined by last price on exchange(s) . It  would be similar to how coinchoose decides profitability. I suppose it could be made transparent about the price per BCX/BTC that the pool says it is trading at and where it got the figure  eg. cryptsy , coinex , vicurex , etc . wherever the coin is exchanged...  then you could check your figures against the exchange to prove that and  to determine if you are being paid or charged properly by the pool.  So it wouldn't need to report to the coin . As for trust anyone who is mining can check their figures against what the pool reports and what they pay.