Honestly I vacillated for a long time on which tier to volunteer Kate for, and in the end I picked tier one hoping that if I change my mind down the road she could eventually progress to a tier two position. I would really like more story opportunities for her, so the more intense regiment of tier two appeals to me for that reason, as well as the fact that she doesn't have a huge reason to get back home like Steve does, but I also don't want to commit myself to something very time intensive right now until I know for a certain I can handle it and won't gum up everybody else by being slow (and I need to poke at Kate a bit more to see if she could really pledge that kind of fealty to Starfleet and mean it).

So, Kate Barlow is charismatic, charming, tough as nails, intelligent, and a very good shot. She's spent years fighting the law, but if that won't hold her back she has no reason not to fight with the law out here in space. She's viciously loyal and tends to step in when she sees cruelty of any sort, especially to somebody who can't defend themselves. She also has a dear friend signing up, in the form of Lady Marian. So these are the main reasons I think she might be a good fit for tier one.