R0J0hound I was messing with your plugin and managed to get unique textures per instance by mostly just removing 'type' in the runtime.js in some places where it occurs. Apart from breaking the initial texture (it's just black now), it does load new images fine and works as expected as far as I can tell.
Are there reasons why the Sprite sheet plugin doesn't use unique textures per instance or did it just happen to come into existence like that? Because I would deem it much more useful with unique textures, for the often mentioned reasons like dynamic use of tilesets.
I guess I would like to suggest to you to change your plugin to have unique textures per instances or release an alternative plugin that does. I'm very much convinced you know what you're doing and therefore I'd rather much use something you made than my own mutilated version of your stuff.