2.7 is very popular
many of the FMS procedures do not work very well in G550 at 3.0.....not quite enough margin before the POWER anuc, and loss of auto speed looms.....set 2.7....
true on G450 too, often set at 2.5 there, same logic...
certainly not FLC at TOD, and 4-5000 fpm downards......
glf