I’ve tried reading comics on an iPod. It really didn’t work for me. I’ve tried the browser-based app from Comixology to read comics and that didn’t really work for me either, and neither do CBR/CBZ readers. So I remain with paper issues and trade paperbacks, but an A4 size tablet might do it (and I could afford more comics that way).
Will be interested to see how Apple’s enforcement of in-App purchases affects this too.