I have a pro also. I haven't done any mods on it yet but do need to seal it. I've never had to use the door to vent it. Using the side vent provides enough adjustment. I've also started using logs in it and it will hold temp for an hour or more now. I also always keep the chimney all the way open, I just use the side vent on the fb to adjust.
Char Griller Pro and Akorn