You know enough about photography to be aware of the limitations of such devices (lower quality, slow focus, etc), so I won't go into that. They are far too slow for fast military aviation (you'll need luck and good technique), but ok for airliners, GA
My experience with this camera category is that one of the key areas to go for aviation photography is the ability of the lens/sensor combo to resolve fine detail. These cameras have noisy sensors, so noise reduction during image editing will be necessary and how well the image can take it will be critical. The better the combo is at keeping this fine detail, the better the final image will survive the editing required to produce the final image. I wouldn't use the noise reduction built in by default, if it is just a standard NR technology. PC
based software will do it better. Might be worth seeing if the Manufacturers have come up with new model specific techniques built in though, they might do a better job than they used to.
I've found that the Panasonic range has good glass in it (or had, not sure on current status, but I doubt that has changed). The sensors are amongst the noisier end, but the images seem to come out ok after processing. This is one my wife took a few years ago with her Panasonic TZ3, 7MP, 10x zoom (28-280mm). I edited it for her, using a quick and standard workflow. Makes for a handy walkaround camera and she's got shots I couldn't get with my more expensive kit.
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Photo © Bambo
I would suggest using www.dpreview.com
as a jumping off point as they have indepth reviews and samples. Start with a recent, similar Panasonic model as a baseline and then see which ones seem better or worse than that. It does take a bit of work (it's a very crowded category!), but I guess what you are really after is to make sure you don't buy a lemon.
Sorry I can't be more specific, but I think this will get you started in the right area?
That's me in the back seat of G-LOYA by the way!