Here is another reason for upgrading to 4.3: holder collision check in the simulation. From the madCAM website:
Take a look at the attachments. I intentionally created a large diameter holder with a short tool.Tool holder collision (When simulating 3-axis with Entry Level, Four-axis or Expert Level)
Tool holder collision is shown in the simulator now. If setting the toolholder diameter for the saved cutter, the chuck collision will show in red color if colliding with material.