The Gerber File Format Specification: https://www.ucamco.com/files/downloads/file/81/the_gerber_file_format_specification.pdf have an interesting revision note from December 2012 on page 15:
G36/G37. The whole section is now much more specific. An example was added to illustrate how to use of polarities to make holes in areas, a method superior to cut-ins. See 4.14. We urge all providers of Gerber software to review their handling of G36/G37 and to use layers to create holes in areas rather than using cut-ins.
and more interesting stuff on page 27:
Processing Gerber files is inevitably subject to rounding errors. Contours must be constructed robustly so that allowed perturbations due to this rounding do not turn an otherwise valid contour in a self-intersecting one. See 4.20.2.
and on page 136:
The cut-ins are rather complex to create on output; on input in CAM the cut-ins must be removed and the original clearances restored, again rather complex. Use this more complex construction only if there is a good reason not to use the anti-pad method.
Are there any plans to support this anti-pad method in the future releases of KiCad?
Have anyone had problems producing PCBs from gerbers that could be traced back to rounding errors in cut-ins?