I interviewed successfully last week. I would recommend getting the gouge for the Delta interview. If you can answer the technical questions for the Delta interview. That is, if you know why the answer is correct and not only the correct answer (i.e. know the math formulas), then you will be fine for the UAL interview.
The HR portion of the interview had no surprises. Have some good TMAAT stories. If you have gouge for interviews, then you will do fine.