It's horses for courses, really...
My boss wants to do Singapore to London City, park there for a while, leave London City for White Plains. On the way back, stop at St-Tropez or maybe Saanen (LSGK), then home to SIN (leaving from a longer runway than either Saanen or St-Tropez). So there is really only the 8X for him, and up to now we did this trip with the 7X, with a fuel stop on leg 1.
On the other hand, if you substitute Northolt for City, Toulon for St-tropez and Bern for Saanen, the G650 can do it faster (total time saving in the air about 2 hours!), with more cabin options, and possibly with a slight edge in dispatch reliability...