Which, on one such cutter I used, involved having to pre-process DXF files through Corel Draw (!!) in order to get the cutter software to read them at all. In my case, that meant a workflow of:
CAD software
-- export-to-DXF
pre-process in Illustrator
-- laser kerf allowance
-- layout parts on material
pre-process in Corel Draw
-- load and reexport the DXF, just 'cause
load in cutter software
-- mark up paths for cutter parameters
(speed, power, cut/raster mode)
For comparison, Ponoko cuts out the last two pieces of software. AI or Inkscape can be used for all required workflow steps. The (necessary) tradeoff is that you have less control: only "cut" or "engrave" to parameters pre-determined for the requested materials.