you might need to keep in mind that switches are meant for light plastic caps. i don't know how heavy a zirconium cap would be, but if you've used an aluminium cap on an MX stem before, you'd feel the overbearing weight of the cap on the low force spring, and the increased wobble on the little plastic stem. doesn't give a great typing experience
that being said, exotic materials are always welcome for artisan caps intended to be used individually and sparingly