What I did was write a post-post-processor of sorts that takes the .nc output, watches for tool changes, and using the tool library information automatically assigns ATC slots, renumbers tools, and generates pauses if collet changes are required (e.g. changing from a 6mm shank to 4mm or to 3.175mm).

That means I can now look at a list of assigned ATC slots, put in the correct tools, and let the machine rip, only pausing for collet changes. Pretty nice and how it should be.

However, I have to say, while the ATC is nice to have, I would not consider it to be the primary factor when buying a CNC machine. Those tool changes don't take long and are not difficult to do manually. It's much more important to get a rigid machine with limited backlash.