I interviewed there... thought it was an "ok" program. Honestly though, nothing I saw there really shined through to impress me. I left there with kinda a "bad taste feeling" in my mouth. Philly is a fun town, but the housing options REALLY Suck too...
They are supposedly "pretty wide-scope", but from what I gathered, Otolaryngology is a powerhouse at that University, and so they take a BIG backseat to them unless its "mandibular trauma." They also lost a few residents in the last couple years.
I don't know if some of what I saw had anything to do with competition with so many other OMFS programs in close proximity.... Christiana (in Delaware 30mins away), U Penn, Temple, etc...
As far as research, most programs are cool with it, unless it turns into a "full-time" thing. If that's the deal, special arrangements usually have to be made. I know that was the case at Maryland with one of the residents.