I would not even consider putting a metal bobbin in my embroidery machine with the drop in bobbin. But when doing embroidery, you have a machine that is really doing a lot of stitching at a rather high rate. It's a two year old machine and it was designed for plastic bobbins. And they do expect the bobbin holder to wear, it even came with a spare.
I use metal bobbins in most of my other machines, but they were all designed to use metal bobbins.