The number of non-paying buyers has increased enormously by the sound of it.

That's just it, it is a perception with no evidence other than the fact that a few sellers are reporting an increase. If every seller who had a decrease in non payers came and posted here who is to say there wouldn't be more of them put folk only tend to come here when things go wrong, not when they are going right.

I have had an increase in number but it is actually a decrease when compared to the increased number of items I have sold. I certainly have had no increase in the percentage of non payers since the option to leave negs for buyer's was removed.