"Even the idea of cartoons or literature for paedophiles makes me feel sick."

It's still true to say that these types of erotic materials (unlike videos and photographs of real children) do not exploit and cause no harm to children. I also think that they represent a useful avenue for paedophiles to - for want of a better term - find some kind of outlet for their sexuality. As a pragmatist, I'd rather these kinds of materials were readily available, fully legal (not all harmless paedophilic materials are legal) and non-stigmatised. What happen's in other people's heads is their business, I'd just rather it stay there.