For starters each cart unlocks which paper settings you can select via Epson's driver. Ones that are not "photo" media options are greyed out (non-selectable) and vice-versa. I also have a R2880 I'm toying with and found that out when I couldn't select matte paper with photo black ink cartridge installed.
To address Cobra's 9-color offering per my experience, a month before they ended the speakeasy process by which to order the "high temp inks", I ordered ink for an Epson Stylus Pro 3800. I was sent one bottle of black ink and instructed to fill the matte & photo carts with it. Since I never planned to switch printer's driver over to photo black to avoid wasting ink via the unavoidable ink purge to do so, I used a few options to ensure ink in the photo black cart got used before it got old. But today I see the offer matte black and photo black sublimation inks?
In regards to what Cobra's web info, I believe their web admin is probably their ink guru. And he can't possibly catch those typos along with answering emails/phone calls, R&D, etc. I say he does a pretty decent job from what I've seen elsewhere.