Amazen proved itself to many of us - BEFORE they were asked to become a sponsor here on LTBBQ.
That is certainly true for me. I have both a 12" and a 6" and love using them both.
The biggest drawback that I see with the Smoke Daddy is that you have to modify your grill to use it (drill a hole in the body). THAT could void a grill's warranty!
There are no warranty concerns with the A-Maze-N pellet tube.
The biggest concern with a pellet tube is making sure you place it inside your grill/smoker where it can get good airflow, so it doesn't smother itself out.