Was out today using the 200-600 with OSS2 and image stabilisation in menu set to manual 600mm , can't say I noticed a big difference so far but will keep trying it in manual and auto . I also tried OSS1 again, definitely don't like that one so will keep trying both OSS2 and 3 . I do think OSS2 maybe better than 3 for perched stuff especially if you struggle to hold none tracking small focus area on the bird .
Since installing FW1.2 when it was just released I've only had a couple of times I had to remove battery .
First time was a few weeks ago eye AF locked on a bird and was stuck in same place even if you moved about off the bird . Soon as I let go of tracking green box disappeared , if I pressed tracking again it grabbed the eye and stayed in same place until letting go of tracking . I removed battery and put back in, powered up it was fine and tracked the eye as normal .
Second time was the other day , I put in a fresh charged battery and powered up , it failed to read either of my cards and gave message unable to read cards , re-insert . I removed battery and put back in, powered it up and it was fine .
The only other thing I find annoying is when photographing birds in reeds especially if it lands on a bullrush in those reeds (not as bad as my A9ii) . If I'm using flex spot small no tracking the focus sometimes goes onto the reeds and seems to just ignore the bullrush even if the bullrush is in middle of EVF . If I do the usual point at floor and back at bullrush the focus is straight on the bird/bullrush . Since FW1.2 I seem to get this more often although it could be me .
Apart from this I enjoy using the A1 , the customisation is brilliant . I would love to know how well the A1 200-600 compares against Z9 500mm PF . I've tried my friends Z7ii 500mm PF , obviously not a fair comparison especially for fast moving smaller birds or faster BIF