I, too, handled one of these ‘beasts’ at Birdfair. I, too, found it chunky but, strangely, not heavy. Unwieldy ? I’m not sure. That would depend on how well I familiarised myself with it, after using it for a while in the field. Certainly, there was a profusion of buttons in different places from those on my FZ-150; and some of these seemed inordinately small and in inconvenient/awkward places.
What manufacturers sometimes lose sight of is the desirability for ease-of-use and speed-of-use, when under ‘pressure’ to obtain a good shot.
The comparison I checked was the ‘zoom figure’ at 5M, using the EOZ (or internal cropping), which is my usual operating setting:
FZ-150 37.5x
FZ-1000 32x
Is this significant ? (It’s well over 10% difference.) I think it may be and am, thus, hanging fire. I believe a replacement for the FZ-200 must be due soon and will wait for this, or for favourable reviews of the 1000 after use on birds and smaller creatures in the field by members.