The 10x42L does indeed "shimmer" when panning. This is not a problem -- it is just something that they do. One just has to decide whether or not they want to put up with it.
The 10x42 Canon would not be a good choice for a situation where you have to constantly change focus, such as chasing warblers through the canopy at fairly short ranges. Otherwise, they are an amazing binocular......
Very interesting.
Your visual sensitivity must be higher than mine, the Canon shone imho when tracking flying birds, allowing stable views against a moving background.
I don't quite follow the problem with 'chasing warblers through the canopy'.
It is a fact of life here in NYC's Central Park, the warblers are almost always way overhead, 30-100 feet up. The stabilization is a huge help getting a good view of the bird. The small changes in focus as the birds constantly shift position by a few feet are never an issue.