Should you get your nordic skis ground?

The simple answer is yes.  A grind refreshes the base and allows the ski to handle broad ranges of snow types and temperature ranges with more efficiency.  Skis generally glide best when the bases are flat.  Skis that are being used and ironed are changing and deforming.  Over time and use bases may deform and become concave or convex.  Surface damage is also a risk whether from use or storage.  Damage that can be fixed, includes: surface scratches, white or oxidized base material, or skis that are no longer flat (concave or convex).  How often should you grind skis?  This really depends.  Could be multiple times per season or every few seasons.  Give your skis a fresh stone grind and your enjoyment will increase with smooth, fast feeling skis.