In the FSI document "G550 PTH", on Preface, page MTP-1, Gulfstream has stated that FSI is in fact their training partner, and that documents produced by FSI, are adopted as standard procedure for ALL Gulfstream aircraft.
On Page 19-13 (Rev 5.2, Oct 2011) it states that at 400 Ft AAL, the command "Flaps Up", Flight Level change" shall be given.
If you can get a hold of this document, it provides excellent standards training for pilots new to Gulfstream aircraft, and anyone flying an older generation aircraft where training documents may be lacking.
I'm not here to start a fight gents, just sharing what I got!
Hope this helps
FR