1) Export original geometry to a CINT file
     gGeoManager->Export("original.C")

2) Export modified geometry to a CINT file
     gGeoManager->Export("modified.C")

3) Strip out patterns which match a pointer reference
      sed '/_[a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9]/d' original.C > original.stripped
      sed '/_[a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9]/d' original.C > modified.stripped

4) diff will reveal any problems
      diff original.stripped modified.stripped