I did aways during these months. It was not a problem and in some ways its good because its closer to the interview selection date and the PDs tend to remember you more than the person who did the rotation in July.
A big disadvantage is that October its a little late for a letter (September is ok). If you need to get a letter from an away you may want to consider doing it earlier. You should know that depending on how the rotation is set up you may not have enough interaction with one attending to get a great letter. On one of my aways I got to work with everyone in the department but I never worked with anyone more than two or three times. I think it is a little risky to ask for a letter from someone you don't know well even if it is a big name. But that's just me.