Yep! It was a thread I started lol. I was using key shavings in clear glaze. I got deep greens at ^06 where the shavings were densely populated. At ^6 I got white, light green, and a lot of blue variegation. I did a simple test at ^06 once and incorporated it in clay and slip but no melting action happened. I never did that test for ^6. J baymore and others noted that the key composition is not primarily copper, nickle, or steel but can actually have a high amount of lead. You can also get further evidence on that because there is a lot of warnings out there to not let you infants suck on you keys as toys.
So really it depends on what you fire and make. If you never do functional ware then have it! The lead vapors "infect" you kiln and will hang around. So if you only have one kiln and do/plan to do functional ware for food uses then I would opt out of such an experiment. You might risk contaminating you kill with lead and then in turn your wares.