The cost to operate a large plane can be more. The cost to reposition a large payload plane can be more. You could end up paying a premium for the lost opportunity of using the aircraft for such a short hop limiting the asset use in a more lucrative booking. If cost is a key driver. I would present that to the agent with your offer to be flexible if it will save the group money. Otherwise you may get the most convenient and comfortable option at a premium cost. We have paid much less moving our guests around in groups of 4/5/6 passengers a hop.