RRF3 isn't so bad really. There are even some example config sets using RRF3 to compare against. https://github.com/Duet3D/RRF-machine-config-files/tree/master/E3D_Tool_Changer

@T3P3Tony what kind of trigger do you have in mind? I was something like that but didn't found yet how to actually do that.

Yes, a switch on the carriage and a switch on each dock wold be ideal. The carriage switch would confirm that a tool is loaded, and the dock switches would indicate which one it was. I've been working with my tool changer yesterday and today. I've managed to get stall homing working on the coupler, and I am developing a set of configuration files for RRF3 on Duet 2. I'll also be moving the origin to the centre of the bed, which is what I use on all my 3D printers.