The problem with non-wood instruments are two things, tone and the number of makers that provide this as a feature.
I've heard that material doesn't matter when it comes to producting a tone in a woodwind instrument. That being said, I would never play a metal piccolo in such an exposed setting as a pit. Pearl is making a Grenaditte piccolo (which I'm pretty sure is the same a buffet greenline), but I fell in love with a Burkart, who don't offer it as an option as far as I know.
Now I'm all for the greenline thing, I play a greenline R-13, but unfortunately if I preferred selmer clarinet's I think this would be the same problem. I oiled the bore with Almond oil, so hopefully that will help with water retaining.
I bet cracking can happen, but the instrument probably isn't as prone to it as an oboe or clarinet.