They are only popular because they are mechanically simple WITH MODERN ELECTRONICS. You can not fly a quad without computer augmentation.
Yes, and? I didn't suggest attempting this with obsolete, unstable old hardware. I really don't see your point. Quads with camera mounts and "modern electronics" (meaning GPS, compass, active pitch control/tilt sensors, altimeter, rock solid XYZ hover with no control input, auto-return) start at about $470. They get even better from there. A trunk full of them is within the budget of almost any S/R group with the willingness to stand in intersections for a day or so with hats and signboards out. Or courtesy of one or two kind benefactors. First thing I did after flying my first one was pull my jaw off the ground and go right back and buy the rest they had in stock. Had to be done, really.
I can take one up, hover it, take a stable high resolution image, move it, take another stable high resolution image, etc. This means even when it's getting dark, I have better detail -- and lower noise -- because I don't have to have such fast exposures. Bring it back (no landing strip required), swap quads and go back out on the next radial, while the crew pops a new battery into the just-returned unit, repeat every ten-fifteen minutes or so, and keep doing that while the images are checked over carefully. Out on one radial, in on the next. Full circle till you repo to the next GPS indexed location. Works great.
Gimbals... the quad can spin in place. While hovering in an extremely stable manner, for that matter, or spinning/panning while working through any set of heights I choose. Be nice to just have a tilt control. More weight. It's really not seriously limiting, nothing like that yet. Should try it though. Tilting the quad itself isn't really possible without it moving, or at least, not the ones I'm using.
While the range/duration would be wonderful, fixed wing requires far too much for this area -- your seaplane is great in some ways, but there's no body of water around here worth talking about for the vast majority of the area. There's nowhere to land. Nowhere to take off. "Wet grass takeoff"? Grass? How about rocks and cactus and nasty, sticky sand? Kind of puts a crimp in fixed wing efforts. Quad simply doesn't care. Put it down (on a rock, on your 4x4 or snowmobile, or just open your hand), up it goes, and you're off and hunting.
Then there are the badlands. Even worse. Not only is there no water, nowhere to take off, nowhere to land, the bloody ground wants to break you -- it's unstable everywhere, either collapsing under you or falling on top of you. Which is part of why people get stuck out there in the first place (wish to heck they just wouldn't go.) With a FW, how do you work down a twisty arroyo that's too complex to follow at speed, and too deep to get a camera angle into because you can't stay over it long enough to make it count? I can just go there and drop right into it and work it right along at whatever rate is convenient. Success? Pop-up and strobe. Awesome.
Battery reload is not the critical issue when you can see better, navigate better, have a more stable platform, get looks into places like arroyos and caves and under-hangs and under trees and bushes that would otherwise completely block your view, and remain on station instead of having to fly by repeatedly when it's called for. You can hover and think instead of getting further from a point of interest with every moment. Battery reload is nothing. You bring em back, instantly take another one off, while that one is reloaded, charge packs as required, no problem. Preparation is key, of course -- but it certainly isn't a problem or even a challenge. You still get essentially 99% active search time without overlap -- or underlap. I throw a trunk in, grab my crew, and go.
Aerobatics... that's an interesting undertaking, but not relevant for my use. Although I've seen people do some crazy things with quads, my own interest is strictly useful camera work. I have shots you simply can't get from a FW platform. Impossible. Quads are *wonderful* already. And of course, like everything else, they keep getting better. And with practice, so does the pilot, although they are about a zillion times easier to fly right out of the box than FW r/c aircraft, or at least any FW r/c aircraft I've ever had the pleasure of flying.
Best of luck in your endeavors. Don't rule out quads!