Bob – FYI.
1) I have a little KX1 running LinuxCNC. Other 1 problem with a stepper motor driver setting, the thing just works.
2) Have a friend with a Tormach 1100 – big machine. Was looking at a 770, but don't think I have the vertical room.
3) look for G0704 conversions – you can purchase kits to do the conversion fairly painlessly. The "G0704" vertical mills are sold by many companies; locally, I'm sort of looking at a "King Canada KC20".
4) The KX3 is between the KX1 and the G0704 conversions in terms of size.
5) spindle speeds – my KX1 runs close to 7,000 rpm – great for small cutters in brass, but not good for slow speed larger milling cutter type of cuts. The g0704 style machines are limited to something like 2200 rpm, and have a gear change for high/low speed ranges.
6) I do have a blog with some things on it, focused on getting us model engineers up and running with CNC; I'm trying to target the common "Model Engineer", not the outliers who are either experts or will never touch a computer in a workshop (both valid – not a complaint) – go to "http://cnc-for-model-engineers.blogspot.com", and feel free to throw questions back.
7) There is no wrong choice, only differing opinions and suitability for your requirements.
Regards – John A. Stewart