Yes, all good points. As a matter of fact the people that I know who are making the most money ($1500 - $3000 per shot) have gone to the extendable masts. I purchased the "Beasts" in the off-topics thread from one such person.
I would argue that it is all about one thing: "What is your mission?" I found the DF an extremely useful tool for close-quarter surveillance type work, but weak in other areas. I started off with the DF because I felt it to be small, light, easily deployed, and safe around people and property, all of which were true. However, those same features became shortcomings as the demands of the mission increased. Couldn't fly in any kind of wind. Couldn't lift a heavy sensor package. Orientation problems at high altitude.
As far as "lethality", that's a bit of a red herring, and mostly based on fear of the unknown. The larger helis don't need to get in close to get the job done. I was very concerned about this at first too, but have found it to be a non-issue. In terms of cost, almost any conventional (e.g. single rotor) helicopter is a far better bang for the buck, if not outright cheaper from the get-go.
So I guess my point is, I can't see anything that a quad can do better, when it comes to being a real work-horse. The one major exception is surveillance, where devices like the MicroDrone excel in the urban environment.