I actually did an away rotation at a top 10 medical school/hospital and was worried that I would look like an idiot since my medical school was not on the same level and the students I would be rotating with would be these geniuses but I just prepared as best as I could before and during the rotation and worked hard with a good attitude and everything turned out ok. CHF is CHF whether its at Johns Hopkins or Eastern Bumf**k OSH
Were you going to rotate at the top 20 IM hospital with the intent of applying there ? The only reason I ask is that a majority of those top tier programs are not really DO-friendly unfortunately so just FYI. I trained at a top 20 program and they don't take DOs. However, if you are going to rotate there just to try to get a good letter from them, then go ahead by all means