Eventually spriter will suport skeletal animation with quad deformation, so in some form per-vertex data will be needed. It might get complicated, because one bone may influence multiple vertices on multiple sprites. I'm not sure if the current structure of the file format will be able to accomodate such data, when the feature is ready?
Also, I'd like to second the JSON file format feature request. JSON parsers are generally significantly faster than XML parsers. And these files will have a lot of data, and being able to parse them during runtime would be nice.
