well, I'm kinda torn about the first rule (don't kill in one combo)
people keep saying that it's really hard for tia to even get a hit in (maybe they're wrong?), and Seraph kept Shadow out so much, why isn't it fair for Shadow to take him out in one shot? but like you said, if you mess up just once, there goes your life...
maybe it should not apply to tia?
I definitely agree with the second suggestion