Perhaps a better comparison is to take a developer that is not...

Perhaps a better comparison is to take a developer that is not yet in production but has a DFS and is the subject of a bid auction to takeover. CDV has reserves of 5.1Moz defined and resources of 6.99Moz. These figures are appreciable and large enough to give comparsons to DEG.
If I exclude the estimated capital cost for CDV to construct a mine and processing plant, then the current SP of 72c produces an EV to Resources of $56.9/oz and so lets take this as a lower limit for valuing DEG.
Don't forget DEG has still not defined resources at Hemi, let alone reserves, and so excluding the DFS estimates for CDV is appropriate.
If Mallina overall can give 10Moz of resource, then using the current CDV valuation of $60/oz in round terms, we get an EV for DEG of $600M, whereas the current EV for DEG is already $1215M!
I am inclined to think that a) CDV is undervalued and b) DEG is overvalued. However, given DEG's current stage of development, I cannot see it having a higher ratio of EV to Resource than what CDV finally sells for.