That said I would describe the risk as possible but low. Being an LCD, as opposed to Plasma, and an OEM from Samsung (iirc) of the professional display line, these are pretty hardy units. The risk is there but if your content changes fairly frequently it should only be a problem over the longest of time scales. In other words you'll likely replace the product under normal depreciation/life cycle first.
you can also use rS-232 to turn the display off when it is not in use, e.g. after hours.
my field experience to date has not seen any burn in issues, but ymmv.