I've been thinking about the whole issue a lot. Kush is certainly a key episode for that; I've also wondered about, for instance, the Nubbins (why not release them back into their natural habitat, with their natural predators, instead of keeping them drugged in the lab?) and the vampire squid in Next Tuesday (it's gentle and intelligent, so let's grab it!). I did wonder specifically about Sally, too, and why she wasn't with her own people. She might have travelled back and forth (before the other merpeople were wiped out) but that's pretty complicated logistically.

As for Kate, she's growing on me a bit. The actor has toned her performance down, thank heavens, and the writers have given her some personality besides "hot kickass chick."