Yeah, but a hacker who wants to add all that but maintain compatibility would likely try and go the Time Capsule route and filter what heads into the link rooms when connected to a vanilla game. At the very very least, a bunch of hacks keep link functionality so that their player's can link to each other while playing the same hack which the OT thing partially botches. I'm not saying that your solution isn't great and perfect for most people, I'm just saying that those that are worried about compatibility will naturally have workarounds to keep all of the new innovations while maintaining it. Those hackers are probably going to feel that losing OT info is too big a loss.
But like you said, once the knowledge of how to compress, hack the boxes to support the new format, and decompress/regenerate when withdrawn is out there, people can tailor this to their needs. So the point is moot (unless someone somehow magically comes up with a better way to do this that we're just not seeing that preserves more with less).
