The frequently overlooked advantage of the 300C is that it is actually a 2.5 person carrier, meaning even two 250lbs guys could fly it in summer with 30gals of fuel on board.
So while in reality it only provides space for 2 fully grown people, it has extremely fine hot and high capabilites for a trainer.
In the competition you'd have to do the math at ISA +20, sacrificing range and whatnot.