Epson R2880 & R3000 B&W print costs

I am considering buying either the R2880 or the R3000 for mainly B&W printing on fine art paper (Hahnemuhle photo rag for example). What would be the cost per print on fine art paper using B&W mode? (matte black, not glossy)

How many prints can be made before the ink runs out?

Comparing both models, will the difference between 2 and 3 picoliter be noticeable with the naked eye?

Thanks.