LightBurn does properly import DXF polylines, arcs, ellipses, bulge corners, block inserts, negative extrusions, and NURBS splines. We don’t have a NURBS representation in LightBurn, so they’re segmented, but can easily be run through the shape optimizer to convert to Bezier splines.
I haven’t looked at what would be required to import DWG files, but they’re significantly less common, and everything I know of that can emit them can also export DXF.
You can vote for the feature by clicking the up-arrow above the number here on our feature request site:
You shouldn’t need to export R11 files for LightBurn - It handles pretty much everything in modern DXF files, and if it you find something it doesn’t handle that you think it should, email us the file and we’ll work at getting it supported.