This is looking really nice. You might want to bear in mind that there are generally two types of ice: old ice and new ice. The old ice is the shiny blue and the new ice whiter and more powdery. The new ice can form a thick layer on top of the old ice.
Also, World Machine has a very handy tool for adding snow on top of a heightfield based on snowfall deposition and other variables, which can also output a mask. It takes a bit of getting used to, but can enhance a scene of an ice sheet considerably.