Lulo currently is alluvial mining/processing and Kimberlite...

Lulo currently is alluvial mining/processing and Kimberlite exploration whereas Merlin is hard-rock mine feasibility.
The skill sets required are complimentary in some areas and differing in others and Lucapa have the technical skill set to do both.

As of right this minute Merlin is significantly closer to becoming a hard rock mine than Lulo. They have the technical data from 4 years of Rio Tinto mining as well as the mine deposit data and diamond data. They also have staff that worked at the mine during Gutnicks reign of terror, so have an understanding of the complexities of the mine.

While I agree focussing on Lulo alluvial production to assist funding the Lulo Kimberlite exploration is number 1, why would you wait on Merlin if it can be shown to be an economic mine? Assuming financing is arranged.