Sad to hear you are going to be trading it in, however I completely understand the whole ordeal you just went through with rust and would rather move on. I'm celebrating 4 years with my WB hatch myself and I'm happy to report I don't have any indications of rust. I am hoping I am one of the lucky ones and I would never want to go through what you just went through with your car. Having said that, I am glad you fought all the way to the end and having this resolved should be an accomplishment for all Mazda3 owners.
Any chance you'd selling your Premium black/blue floor mats? Its only right, they end up in another WB. haha.