So airberlin finally got back to me with a 100 euro voucher offer.
I replied with a letter of action and they basically said go ahead. So I don't know if I should try LBA, fill out a Mahnbescheid, or just go straight to small claims. I'm based in the US so not sure if I file here or in Germany. Euclaim's fee seems high and the other thread basically recommended actions for UK based ppl.