There is a lot more to this than has and probably will ever be published.
Darmah is on the money, regarding platforms in the end there were two similar types and the criteria for selection was blured.
Big issues were as follows:
Ability to depart max fuel and then have the tasking cancelled...... how long before you can land due max landing weight??? There is a 10000lb difference in the 604 between MTOW & MLW. Does this mean the requirement for max fuel each time means that each launch will have a potential 5hr sortie before you can land????
1E DP max range return. Yep this was a doozie the numbers crunched to make this work was a challenge. Lets say you are already out at 1200nm+ from the nearest landing point and you find your target. You get low and slow drop the toys and just as you do that at 100ft @ 130Kts you suck in Percy the Pelican into #1.......
But that's not really the problem, the problem comes in when the drop master calls up and says he cant close the door.
OK 1E return, not a problem, slow climb back to altitude, yep you will be a bit slower but the altitude will help with the fuel burn.
DP return, no problem get up to FL110, both engines and you have the speed.
1E DP..... there is the limiting factor, the return is slow, the fuel burn is high and that was the performance challenge.
I don't know what the actual numbers from the 604 were but product B could do 1200nm+
The next criteria was the amount of crap required to be carried. Ask anyone at the current operator what happened to the doorknob. More and more stuff went in to the point where it bulked out.
The 604 will be tight to begin with, Product B offered the ability to carry the 5 crew, plus the laundry list of toys to throw out the door..... +5 more pax, ie an entire relief crew.
All of this was meant to be done in a $27M p/a budget...... Yet the winner made a non conforming bid at $53M p/a, and one of the used the same aircraft.
Will joe public get a platform that is better than what exists?..... yes it will. Will the taxpayer get value for money? you make up your own mind.
