Maxed out, all units have a stat cap total of +3 from class bases so if you max stats in all classes and have all the same skills, they will cost the same.
Spotpass Pr. Marth has 3 unique skills too but males get one less class than females (Fighter, Warrior, Berserker, Barbarion, Demon Fighter) (Peggy, Falcoknight, Dark Flyer, Troubadour, Valkerie, Bride)
All other classes they can all get access to.
So with no exclusive skills, a female has 1600 cost more than a male with all normal skills obtained.
Add on the extra skills for 800 each, and est comes out on top.