Here is a link to Jerome's fine article upon the launch of the 976, which has some interesting details on the caliber:
And a scan from the same article:

I can't resist adding a scan of the 822 for comparison's sake:
(Photo is by Nicolas, JLC Forum Moderator)
I hope neither Jerome nor Nicolas mind my using their images for this post.
I have to say, performance issues being equal, the 822 is a much prettier movement to my eyes. And it is hard to argue with its 20 years of in-the-field testing.
Best,
respo