The Falcon 50EX, with its three small TEF731s, takes more weight off a shorter runway a longer distance at higher speed with less fuel burn than many of its two-engine competitors. I have no hard data to back it up, but I'd bet a 50EX slowed way back to .78 burns less fuel over a 1000nm segment than a Hawker 800 at HSC does.

The 900EX also has more range than G450 on substantially less fuel burn...but it weighs a fair amount less than the Gulfstream too.

As far as engine costs go...a three-engine plane doesn't necessarily mean 33% higher costs. Three engines don't have to work as hard (produce as much thrust) as two engines to push the same weight, and because of this you can use smaller (and less expensive) engines. As an example, the three TEF731s on the Falcon 900EX only cost 10% more to operate vs. the 2 RR Tays on the G450, but burn 32% less fuel over a 1000nm segment.