i haven't watched kpop star but sohee and minju are both good in that performance
i especially like minju's unique vocal tone. she has a nice rasp to her voice that isn't common with someone with a higher range like hers. i think her voice would be a nice addition to the girl group and compliment lily m's raspy tone that comes out in her lower range.
what i want most from this group is undeniable visuals and irrefutable vocal talent. vocals aren't ever going to be enough for a girl group, because they won't ever shed that idol image of being someone who's pretty. but visuals aren't enough either because in 10 years when they're all closer to thirty they'll need to have talent to sell albums rather than youth.