The big question is the Z axis. You said that you need more than 5 inches of travel. This blows away all the BOSS machines.
The only machine fitting that parameter is the old series 2 NC. It had a stepper motor on the knee and an air cylinder in the pedestal to counterbalance the weight so the stepper could move all this mass up AND down.
If you read all the above answers, I am quite thorough in describing what each machine had. Perhaps it would help you to set up a chart with the features you need, and the features you don't need. Sometimes something visual like that helps.
George
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)