Them potentially violating my copyrights is
very much my business. But you're right, the difference is how much the respective parties have to spend on legal battles.
Simply showing up to court wearing a tshirt that says "what she said" probably wouldn't fly, but I like to imagine that any arguments made by them about their copyrights would be equally true of my copyrights.
At this point I'm mostly wondering if "you ripped me off first" is a viable legal defense to copyright battles where it's unclear if either party is distributing the works of the other. One thing is for sure though, if I were to do this as an individual, the discovery process would be much more expensive for them than me.