I have it and use it regularly, but yeah - deskproto does not support true 4-axis toolpaths, they just run 3+1 (or 3+1+1 for their 5-axis paths). And unfortunately there's no compensation built into their toolpaths, they don't really have any QoL things like adaptive toolpaths (or even things like continuous pocketing), their acceleration control is -garbage- so you really have to be careful doing anything difficult like copper, the list goes on.
Honestly the tl;dr is that it works fine if you're using a CNC router, and you're going to have a pretty rough time if you're using a milling machine.
Unfortunately there are essentially no FOSS programs able to produce engineering parts, and even fewer linux-native CAM programs at all. It's really a huge gap in the FOSS world (driven largely by it being an incredibly difficult problem to solve)