I've been considering going back frost myself and seeing how the shatter spec compares to my deep Fire build. I've been Fire since the low 30's or so and basically just stack my team, cast flamestrike @player, blastwave, and spam flamestrike with an AE at the end to finish off the last bit of hp.

The spec seems to do fairly well and its nice getting a few stuns with the fire build. I do wonder if I could move faster though. Only averaging about 30k xp/hr right now at level 57 in BRD.