Many thanks everyone, very helpful.
Does anyone have any data on the operating cost differences?
As for suggestions of a G550/Global XRS, we looked at those, but the operating costs were way beyond what he is willing to spend (even though he could afford) as most flights are within EU. Space-shuttle-driver, that's not a bad idea on the charter, will recommend. Flying first class is out, his kids are young (below 6) and he views the flights as his opportunity to spend one on one time with them