All the flavors of Intellicad share the core but some are doing a good job "polishing" it I use Progesoft and I can say that it has it's bugs, I have keeping a track on Briscad and their version is really good, I haven't really tested for full a production because I exchange a lot of AutoCAD drawings and I realized that it was not good enough for me to move to intellicad (Yet...)., for example I use splines a lot and offsetting of splines was only available probably only a year ago on briscad and then for the rest of the intellicad flavor, one other detail is that in most of the versions the auto regen does not work, so when you drag an object (line arc, or circle..etc...) it leaves a trace of pixels on the screen, is not a big deal but IMO reflects that work has to be done to the software.