An interesting subject, the discussion of which might benefit from more information.
The full
NTSB report on the G-650 flight test accident in Roswell is quite comprehensive in it's analysis and an interesting read for anyone seeking to better understand what happened.
The pertinent section of the report as it concerns the difference between stall AOA in ground effect compared to out of ground effect can be found beginning on page 26 (sec 2.3) of the report.
Enjoy!
westhawk