I'm there with you about basically everything that you said, even if just like Asta I can see Rachel's character as inteligent (clever i think is the word that you used) but tough on the other hand.... nop.
I sort of ended up comparing her with Marsha Thomason's character in White Collar. There is not such a big difference in age between the two (a couple of years in RL and possibly none in the scripts) but I have no problem in seeing Diana as not only tough but bad ass.
Hope to eventually see Dr. Hathaway in the classroom. I would sign up for his class.