I bought an expensive Titanium Space Case grinder a few months ago. Damned if it didn't start getting chipped up into the weed. As someone slightly OCD about metals and toxins / particles, this bummed me out and I had to replace the grinder. In researching a better material,
other's noticed this chipping from titanium and it looked like stainless steel would be the best choice in material if you wanted to use a metal (though no one is making grinders out of SS.) I ended up going with an anodized aluminum santa cruz shredder. After this, I find Ti slightly sketchy.
Glass would be cool though. I feel like SS would outperform it in terms of efficiency, but, I'd be curious to see just how it compares. I could put up with a slight loss in efficiency with a trade for all-glass.