At a bare minimum I'd like to get the version of the addon displayed in the error reports that users send. If I understand things correctly, there are 2 basic options:
Override the errorhandler. I could do this but then I'd be fighting with standalone error handler addons like BugSack, so I'm not sure that's a good idea.
Use pcall, add to the error string and then call the system errorhandler. Having to wrap everything in a pcall would be a pain and I don't know what the cost of that would be at runtime (is pcall expensive?).