So apparently, symbol isolation mode isn't aligned to the (global apparently?) pixel grid, rather the paths are displayed aligned to the origin presumably. The origin is not aligned to an intersection of the grid. Thus it becomes very difficult to create pixel perfect symbols. Paths that are snapped to the pixel grid are then redisplayed offsetting from the origin, causing bleeding in the isolation mode. If the origin is specified as the center that is (presumably it would work fine for a corner), you're going to have a bad time.
Is this fixed in CS6?
Also, has there been a feature added in CS6 to reposition the origin as the center of an object?
Okay I have figured out a workflow that generally resolves all the peculiar behavior with align to pixel and symbols.
Do not align to pixel your paths. Align to pixel your symbols. The symbol origin will be aligned to pixel and there will be no bleeding in isolation mode and you can snap to pixel the symbol itself.
You still have to scale/adjust your snapped to pixel paths as they are expanded on a paste for some unknown reason. This is an issue of another thread but may be useful to complete the workflow.
It still quite an issue though that for absolutely no reason, symbols without align to pixel are displayed as displaced from an arbitrary position of the origin in isolation mode. This is a bug I feel in the implementation.
Nevermind, the above doesn't work.
If a symbol is set to align to pixel every object in it gets automaticaly reset to align to pixel in CS6.
Also, why the heck does the symbol isolation mode get exited when the document is saved. Illustrator is really a pile of **** code.
Is there any setting to fix this? This makes symbols essentially unuseable as it becomes impossible to align objects scaled down to look good at the pixel level because such objects do not have easy to work with dimensions. With original objects it's possible to correctly align them numerically. This is so dumb.
Once again, the issue is that in symbol isolation mode, the pixel grid is not aligned to the ruler.