I've got a large 15lb enamel dutch oven. If I am doing any sort of speedy operation where I have to scrape off crusted ingredients, I might do some real clattering about. I have some real good chicken curry recipes where I do this.

It's also worth noting that certain things like home canning might actually void the warranty of your glass cooktop. The extreme weight put on them during the process can actually put more pressure on the layers than they can handle. Older canning equipment might not even be compatible with the flat surface.