A skilled guy can work miracles. I am sure if the dent is on or near the door reinforcement it makes it tougher and the result quality will be reduced accordingly.
The guys who know what they are doing will tell you they can't make it perfect because the metal is stretched, they can only improve it. But they sure can improve it.
I had a dent, not a ding, a dent about 8 inches by 6 inches pushed in about 1 inch and visible fold in the metal. A couple of shops told me it couldn't be fixed with paintless techniques. I found someone really good. The guy spent about 3-4 hours on it and it is close to perfect. Cost me about $500 but he also went around the car and cleaned up a few other minor items.
I know $500 is a lot, but consider the cost of the alternatives. And alternatives would have risked mismatched paint and a poor fitting door. I think I made the right decision.
Little door dings are trivial for someone good.
Chuck Moreland '86 Cab - "Sparky", '77 Targa - "Sweet Pea"