Caroline, thanks so much for the valuable information in your blog. I also try to garden in Cape Town in a garden that is battered by the Southeast in summer and that gets very little sun during a large part of the year. But without my hands in the soil I cannot live, so I persist.
This year I want to see if I can get by without collecting snails at night and dumping them in an open field or unkempt patches far enough from my garden for them not to attempt a return trip. I have noticed a couple of shells of other snails that are predators, but never seen a alive one.
Thanks for all your research and sharing it with others!