X, and in retrospect also Prof. Isi, hold that global constraints on GR GW metric perturbations are not an issue since space is being alternately created and destroyed - not just stretched and compressed. My problem with that remains the same - for transverse perturbations it implies objects e.g. 'sticks' do not scale with the metric so as to preserve proper spacings. For a spherically symmetric geometry like exterior Schwarzschild metric, there is indeed more space created owing to presence of a gravitating mass. All without violating the principle that metric scaling acts identically on everything within - afaik another way of stating SEP (strong equivalence principle). This nice compatibility fails in GR GW situation. How long it takes to exhaustively compare predictions of all currently viable competitor theories is anybody's guess. Won't be soon - unfortunately.