The 300 and Galaxy 200 are galaxies apart. When you start to peel the onion, which GVFlyer sometimes doesn't like to do, the 6'3" height of the G200 is from a dropped aisle which slopes up toward the aft. A dropped aisle in a $20MM aircraft??? The LRC in the 300 is .78, not .75. It's wing is much more efficient than that of the G200. A balanced field length difference of 1,270 feet (that's 20%). Landing distance difference of 610 feet (20%). Direct to 43,000 at MTOW in the 300 versus a step climb-ouch. Boots on a wing? The baggage? External on the G200. Accessible in flight on the 300.Baggage volume on my G200 is 125 cu. ft, 1980 lbs max. Maybe the interior can be customized to add baggage space.
Add all of that to an expected residual value difference of anywhere between 15 and 20% higher for the 300 after 6 years and the difference is VERY easy. GD ought to be embarrassed by their very ugly step-baby.