Hi, cedar -
I'll do what I can to give you a few answers


I have only operated the K2, so that's where my knowledge is.


A lot! There's pneumatics, hydraulics, motors, bearings, and electronics to think about, so consider all that could go wrong with any of those and start from there. Then there's the software updates, tool sharpening and repair, calibration, issues with dents and bash-ups from flying wood...
Maintenance is a major factor with such a precision machine, and it can take quite a while to iron the bugs out. I would even suggest getting one second hand and having the operator train you on that particular machine.


If the machine is properly calibrated and the timbers programed in correctly then the notching will be as accurate as you make it. Plus or minus 1mm, dead on 0.5mm, a tolerance of 4mm...


Yes and no.
It's hard in that you have to be on top of so many things, as mentioned with the maintenance question. It can take a while to wrap your brain around everything it does and what you need to look out for. But eventually you get to know it by sound. This can take about a year.
If you understand timber framing to start with you'll have a much easier go of it. Understanding the properties of wood and knowing how to read shop drawings are very helpful.
Trouble shooting is where you have to be a very creative in your thinking. You never want to have to wait 2 weeks for a part or technician to come over from Germany, so, if you can, figure it out on your own (with technical support from Hans via email and a local welder, of course).


There's another thread that deals with this one


Not quite sure what you mean by this. But it can add chamfers and end details. The machine is still pretty rough, though, and it leaves marks on the timbers from the clamping, grease and saw table polish. So the timbers need to be planed or sanded afterwards.

I hope this helps somewhat.
Peace,
*K