Compatibility between xmp files for Darktable and Lightroom

Software darktable
2
  1. missing lens support PIXLS.US - Create lens calibration data for lensfun
  2. the XMP files are 100% not compatible and the LR to DT importer is very very minimal
  3. did you file the bugs for the crashes you experienced so they can be fixed?
  4. we have people with rather large DBs, so can you provide more details?