Don't drill holes. If you don't want to buy a Vortex, just use what you have or use regular baskets. The food looks really good.
A Vortex will marginally increase airflow rate because of its conical shape. It shield the food from radiant heat, and increases cooking by convection. Your chicken cooks quickly, you don't have to flip, don't reach across the Vortex. A charcoal holder without that shape won't circulate air as efficiently. But if the food is good - it's all good.