It's not quite time to do away with aluminum as the moving element for good quality ribbon microphones. Or is it? Aluminum has been the traditional material used in virtually all ribbon mics since the beginning. It has good conductivity, is relatively low in mass, and can be formed into thin sheets, which is essential. Nearly all ribbon mics made today use aluminum leaf about 1/2 to 2 1/2 microns in thickness.
But aluminum isn't an ideal material. Its mass is still considerable, and that contributes to inertia in the ribbon assembly. Although it has good tensile strength, it tends to bend easily and lacks an ability to return to its desired shape after being deformed by pressure, wind blasts, and other forces.
With Roswellite fast becoming the ribbon of choice, I think the writing is on the wall.