The PD at Mt. Sinai wrote me a solid, great letter, and also got me interviewed at another program, and I'm not a superstar. He is in the top 3 EM docs I've EVER met. The chairman, on the other hand, I'm MUCH more inclined to ascribe the "difficult to work with" label to. It was his direction that I not be ranked (since the only FMG's they rank are from Sackler), and this I discovered after research when I didn't match there, and they didn't fill. I can think, likewise, not filling 3 spots is his handiwork.
As for Elmhurst, I did prelim there, and I can back up the population, acuity, and diversity. If you want a true, great EM experience, you'll get it at Elmhurst (as a bit of trivia, when Noah gets shot in "U.S. Marshals", Elmhurst is the hospital they take him to).