It has better raw DPS than a Vulture (2 med and 1 large vs the Vulture’s 2 large). Besides:
The Diamondback Explorer was Lakon Spaceways’ response to criticism of the original Diamondback ship class. By extending the ship’s frame it allowed greater cargo capacity and so greater mission variety and endurance. It also brought the ship more into line as a smaller brother to the successful Asp line although at much more modest price range. The Explorer model can fulfil the same roles as its companion ship type, but is also able to operate as a fast transport and resupply vessel useful for supporting deep space operations in a hostile environment.
— In-game description DBX
The Diamondback Scout is Lakon Spaceways’ specialist combat explorer vessel. Unlike its bigger brother the Asp, the Diamondback isn’t suited as an all rounder vessel. It is popular with elite recon and pathfinder units with navies throughout human space. Its relatively low cost also makes it a popular choice with independent pilots who appreciate its combat and exploration potential.
— In-game description