I chose metal because it seemed more stable. But I never put the grids in the dishwasher. For very juicy products, I ordered silicone inserts directly from Stöckli, which fit directly onto the grids. This was a great help, because otherwise they would have got stuck in the grids. I can't say whether this is different with plastic. Metal just seemed more stable to me.

I can only agree with these answers. I also have the metal version because it has a finer mesh, but I always clean it by hand.