You may be right, I've never market updated anything I have themed. I don't see how it would know what to update and what not to inside the apk which it would have to be the whole thing for people that don't have it already.
you don't need to android, just use titanium back up to back it up, then if its wrong and you want ijrummys back just install it and install the backup and data and it will be just like before.
I had downloaded the file to make a metamoph of it, but I don't see anything really different. So I didn't waste my time. If he changed the actual program I can't help you there.