No, it would imply that Gulfstream and Bombardier designed larger planes that are heavier, greater cabin volume and longer range--the whole combination being heavier and, yes, less efficient. A 900 grossed out weighs about what the BOW is for an XRS. Big difference.
The 900 has greater range than a 2000 because it was designed that way, not because three engines are more efficient.
GF
So Gulfstreams are heavier than Dassaults and thats probably partly because of size/range and partly because Gulfstream design philosophy is to "build it like a tank" while Dassault is all about shaving weight. Dassaults have better residual values so I don't know how much more durable the "tank" Gulfs can be but I digress.
My point is that if you do the math comparing the newest planes, the G650 has about a 12% higher thrust-rating to MTOW ratio than the 7X. So even being almost 60% heavier, with its 2 massive engine it has about 12% higher power to weight. Why can Dassault have less power and still perform? Because when you eliminate one engine from both, the 7X is left with a 10% higher thrust-rating to MTOW ratio than the G650.
So I'm thinking, can this phenomenon be key to a lot of the tradeoffs? For example, Gulfstreams are known for their low-sweep, no forward high lift device wings designed for climb performance AND ALSO engine out performance. They can stay in the air better with 50% of their power if they have a wing optimized for slightly slower speeds. However, obviously this costs them efficiency at normal cruise speed. The 7X, keeping 67% of its power with an engine out, with 10% better remaining power to weight than the G650, uses a more highly swept, faster wing. Is it possible that a reason that the Dassault wing can be more highly swept is because it doesn't need as much aerodynamic help from the wing in the case of an engine out?
These are the reasons that I'd really like to talk to a business jet engineer. 2 engines are inherently much more efficient than 3, but if the 2 engine plane has to produce more thrust, and it has to have a less efficient wing, and if it has to have more drag because an S-duct engine is more aerodynamic than any tailcone... then I can see how a 3 engine plane can be competitive.
Also, I know that there are many different design decisions that go toward Dassaults' great takeoff performance, but could smaller engines be part of it. One thing I know about cars is that smaller turbochargers spool up faster, and a turbocharger is just a form of turbine. Is it possible that smaller turbine engines on a plane spool up faster and start producing more of their thrust faster than larger engines? Could this have an effect on takeoff performance, or no?