The ROC-DS is designed as a counterpart to the ROC rather than a straight upgrade; it's not designed to be superior in every way, but to have some positive and negative attributes like all of our vehicles. The goal for the ROC-DS is to provide a more efficient per-sortie experience thanks to the larger ore-storage capacity, increased reach of its mining and extraction beams, and the ability for two players to mine together rather than independently. As mentioned on Star Citizen Live, the current method players use to circumvent the inventory limit by unpacking to a carryable box will be removed in a future patch, meaning longer-duration mining expeditions are more sensible in a single vehicle over two.