I've been using a 50/50 mix of coco husk and moss for the last 6 or 7 months. My only complaint is that it's a bit of a pain in the *** to spot clean, since it's like a carpet when it's dry. No other problems so far.

Been looking into straw pellets, but it seems that I'd either have to pay about €20 for small 20 liter (or was it 20 kg) bags, or €155-€350 for pallets of 500 - 1000 kg.