As an autoimmune disease sufferer unfortunately I have a metal sensitivity problem too, I'm unable to tolerate any metal coming in contact with herb or concentrate (severe headaches), so the news that there are ceramic pods to go with the iq2 was a great incentive for me. They do get stained from multiple uses (approx a week of usage, depend on usage obviously), but they persevere the iq2 oven clean!!, the stains can be partially removed with ISO, soaking it for a day and then rinsing the parts in clean RO water afterwords, to dry them and remove any traces of ISO simply line your crockpot with baking paper and put it on high and spread the ceramic parts on the paper, the crockpot will cook any ISO off them.
I found too that I can fill them with hemp fibre (degummed) and apply concentrates on the fibre and get great clean taste vapour, cotton gives me headaches even if organic, so sticking with hemp.