Kai Tsubame has been very surprised at how things turned out in the end. The black challenger proved to be tougher to test than originally planned.
He even forged an alliance of sorts with the assassin siblings. Together, they had taken down a group composed of twenty level 1 swordsmen, ten level 1 bowmen, and two level 1 elementalists. That operation cost him dearly.
Losing warrior and archer classes was acceptable. Those were more common enough. Mage classes, however, were harder to find.
Generally, only around one out of ten humans could become a mage class. Not because of their lack of mana, but because of their lack of raw talent in manipulating aura outside of the boundary of their bodies.
Eventually, one would learn to do so with time, provided the person managed to live long enough. However, only a few, those who showed promise early on, could become mage classes.
So, had it been worth it losing two elementalists? In a sense, yes.