With a lower slope roof you can hang the gutters low enough so that an ice slide flies over the gutter but the rain still falls in. This will help to avaoid damage, although damge can still occur if there is ice damming. Unfortunately this approach does not work with a steep slope roof because the ice slides right into the gutter (as you already know, or you would not have asked the question).
I think that you need to install snow guards on your roof to prevent damage to your gutters. metal roofs are notorious for allowing large snow slides. See the article below from the U.S. Army Corps of Engineers about snow slides and metal roofing. It has some amazing pictures of snow slide damage.