I took the new "Bigma II" out for a test drive last weekend. I was quite impressed. Remarkably sharp for a 10x(!) zoom, it does appear to be optimized for the long end which is often not the case for a super-zoom. At 6 lbs it is somewhat heavy (vs 5 for the 200-500VR), though it's much lighter and easier to handle than my 600E, that's for sure. Compared to the 200-500VR, the zoom action was quick, though stiff with 120-degree+/- twist. AF seemed snappy and OS was quite good I thought.
Overall, I think it's a better performing lens than the 200-500VR, but of course it is more expensive too. Regrettably I returned it since I was looking for a "do-it-all" zoom lens for my Z7 for video work, and the continuous AF chatter was noticeable in the sound track during AFF and the zoom was a tad too stiff for smooth video captures. For stills capture I think it's a really excellent option...remarkable even.