Wow, a month of ortho in your 3rd year surgery elective sounds excessive, and low yield for the shelf exam and Step 2. Time might be better served doing more gen surg and or Plastics, etc...
Anyways, I would suggest doing the home rotation as a 4th year unless you are ABSOLUTELY sure you would not go there, no matter what! It may look odd to not have a dedicated ortho grade from your own school (a good one, of course) on your transcript. In addition, your home ortho department may look upon you not doing a dedicated sub-I as a slight to their program (unless they tell you otherwise). Ortho can be such a crap shoot in terms of where you interview/match. You shouldn't do anything to jeapordize a good shot at a spot at your own program.
Take this for what it is worth from an M4 without a home ortho residency that was only being able to do 1 away. I would kill to have the "home school advantage."
Cheers!
