His point is not valid when his comparison is not apples to apples. The G550 WAS Gulfstream's long-range flagship based on a cabin that was developed over 55 years ago. The G650 is Gulfstream's NEW long-range flagship. The G500 and G600 fit niches that Gulfstream customers asked for.
The G600 wasn't developed to be a DIRECT replacement of the G550. Therefore trying to make a DIRECT comparison between the G550 and G600, as tuna hp is attempting to do, is not valid, and is why he won't be satisfied.