If I'm understanding this product correctly, this is as useless as a grill pan. The advantage of a real grill is that food is exposed directly to the fire/smoke. Additionally, the fats etc. drip down and vaporize which creates additional flavor.
All a grill pan does is remove any advantage of a flat top or pan (meat frying in its own juices/fat) and instead just dries out the meat.
Grill marks aren't what gives the flavor. They're a סימן, not a סיבה.