I've had ADK build a coupe of machines over the years. Like anything electronic, parts can break, boards fail, etc., etc., etc.
When that has happened, or I've had other troubles, I have always found their tech support to be most helpful. As one who is not in the position to build my own, or want the headaches of finding the parts that "play nice" with each other, I consider the money very well spent.
You will find that both the people at ADK, and Jim Roseberry, are very helpful, and you would not go wrong purchasing from either. Both can tailor a machine to your needs, and depending on what you do, you may or may not need a real "high-end" computer.