I got into CNC milling about 9 months ago. SVG to 2.5D problems are easy, and get you to a lot of cute solutions, its about as close to the work flow of 3D printers as you can get.

But the really interesting stuff is when you get to CAM. Multiple tool paths, genuine 3D cutting. Moving the work between paths etc. Its like going from juggling 3 balls (2.5d) to 5 balls (3D).

I haven't seen any competitive opensource CAM products, and its the main reason I continue to use Fusion 360 instead of OpenSCAD or SVG for my designs.