I think preference might be for glass to heat air rather than having coil directly in airpath which is nice part of elev8r design. Also you don’t want coil coming off near your face there is a enough tension that can build up in coil wire that you’d want to damn certain it’s not easily gonna jump off of heater.

I think in terms of material quartz might be a good option despite that boro still work...the mass of glass too is something to consider in terms how much heat it can retain over a hit...elev8r works great because of nubs that force airflow turbidity (could be better...Eg beads) and even the heat of air stream so would also think about how design achieves the same.