The lower head grade will have an impact on the recoveries...

The lower head grade will have an impact on the recoveries including costs...as more waste in the feed is competing with the ore in the plant (reducing grind effectiveness etc) also impurities sneak through and can lower the concentrate grade. The resource grade should hold up though as there is not a lot of local variability in the grade from hole to hole also the lodes are relatively thick. It is just a question of how cleanly they can mine it imo and how well behaved the ore body is...