I've heard mixed things about doing away rotations for emergency medicine. Yes? No? If yes, where should I go and how many should I try to do? Lastly, is September or October too late to do an away (for any field)? Thanks!
Check out the EM specific forum for a lot of good EM discussions.
I'm not sure where you are hearing mixed things. I'm starting an EM residency in the fall and everyone I knew did at least a home rotation and an away. Some did two aways, but that's by no means necessary. EM is a field where letters matter; a great letter from an away proves that you impressed someone who doesn't have the same vested interest in you that your home school does. Just think of it like a month long interview. Having said that you don't need to rotate at a particular place to match there (for the most part).
As far as the timing, September is ok, particularly if you already have a home rotation under your belt but earlier is always better (it can take a while to get those SLOR's written). If your home school doesn't have an EM residency I would consider doing two aways.
Edit: There are a few different ways to pick an away. 1) rotate at a famous program to get a letter from well known faculty. 2) Rotate at a program you are really interested in. 3) Rotate at a place totally different from your home program I.e. rural vs urban, county vs academic etc. I advocate number 3 to give you the broadest EM perspective to help choose a residency, but so long as you can answer why you rotated at a place then really it's up to you.