Copper trashing is basically something you want with an engine. It can be ok for big money, too, - like given the choice between copper trashing and not trashing copper, you'd take it. But the benefit is pretty miniscule - almost never worth the trouble of a missed silver - unless you are building an engine. This is why you see BM/Moneylender infinitesimally better than straight BM. Here, there's no engine in sight.
On the other hand, if my opponent goes young witch, I'd think about picking one up, because copper-trashing isn't that good here, but a non-action moat is ok, and if you can package the two together... I'm still not sure it's worth it, because you want a lot of silvers fast, in any case.