The strength of the unit is that it is reactive.
It's deployment is flexible and based upon what openings your opponent have left you.
It can be either 2 (drop pod and full squad) or 3 (drop pod and 2 combat squads) units to contest objectives.
and they can possibly take out two vehicles in a turn (if in combat squads)
they would take two assaults to be taken out
also if combat squads are not the way to go against a certain opponent you don't have to declare whether they will be splitting or not until they deploy.
Their strength is passive. They don't hunt tanks, they block them.
If it's space you need to pass through, you'll not be able to ignore them
if deployed properly, they will be supported by a full battle line the first turn they come in
also I'm not saying you should take this instead of a Melta-Bike unit, take it with and you have a good anvil with hammer
Loose Deployment example:
a West / Center / East objective ~ mid board
Opponent: ~ 12" east of center line deployed transports, hard eastern flank with armor
Melta-Player: Drop center, near center objective to support 1st turn approaching Rhino and razorback squad
It's really not about the number crunch as much as the function the element with the army as a whole
(they are not as points efficient "on the firing range")
and it's about setting up board dynamics rather than taking a specific shot
Like those first 2 pawns of a chess game.
well, that's the sum-up of my somewhat inarticulate pitch for the Drop Melta-
Devs