Dave's comment about manual zoom prompted me to try and find out if the FZ200 has it and it appears that unfortunately Panasonic have reverted to power zoom from the manual zoom of the FZ30 [8Mp] and FZ50 [10 Mp]. Not impressed by one review I read that they didn't know that the FZ200 reverts to what the FZ20 had [ my first Panasonic] with its constant f/2.8.
This info search brings up a description of my bridge camera, the FZ50 with its Raynox 2020 giving the 950mm reach at about f/4.5 which compensates somewhat compared with what DSLR rigs achieve in their ability to use higher ISO ...I rarely if ever used other than 100 ISO for IQ reasons. Pricewise the FZ50 goes for about $250 s/h and the Raynox 2020 is similarly priced. It shoots RAW if you want to go down that path.
But from memory of researching your existing camera I am not sure exactly what advantages you are going to get ... you already have 500mm reach for the birds or is it 550, not much difference and MFT with the kit lens will give you better IQ for the little beasties ... I have noticed that you rarely go in close with your shots so the kit 14-42 [ 28-84 mm ] would be fine. and like the APS-C worker you have greater tolerance to crop.
The reduction in native depth of field was something I noticed on using MFT but since I normally focus on a subject and ignore softness elsewhere it doesn't bother me these days ... in fact I often deliberately soften further the surrounds to the subject in editing. Which makes the subject look sharper to a degree. Normally working at 800ISO means I also usually am working at smaller aperture which I guess compensates.
So unless something has happened to your existing gear I'd suggest it is MFT or nothing and you will gain little from a second bridge camera .... MFT is a giant step forward for a bridge user .... hope this helps you decide
Note ... my aim with MFT was to get a larger sensor with similar characteristics to a bridge camera and so today I have a 28-280 zoom which is very close to the 35-280 of my original Nikon bridge camera which served me so well before Panasonic distracted me away from it
[ WOW!! 432mm reach instead of 280 and a constant f/2.8 ... the FZ20 and at the same time I bought the FZ3 for my wife which she still uses today a decade later
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