Having enough air to fuel (gas) ratio is one way to prevent back puffs. I used to get them with the Vermont Castings Stove I started out with 25 years ago. The combustion area above the fire bed was too small to allow proper mixing of the air and volatile gasses, so I had to learn to leave the doors cracked a little bit until the flames died down.
The Glenwood will not back puff. You can't make it. I've tried. The large combustion area above the fire, plus; the heated secondary air hot blast ring around the top of the firepot insures that heated air in enough volume is available to ignite the gasses before they build up to that level. The worst you get is a slight, "woof," sound which sounds exactly like a gas furnace when it lights off.
Yet another reason to own a Glenwood Base Heater.