Not sure if you have a different situation than OP. He said he had a project on it's way to publication. Having multiple ortho publications on PubMed is a huge difference. If you have a bunch of pubs in ortho journals, then a research year won't help you as much as if you had zero pubs. Yes, the connections and LORs are probably the biggest benefit to doing a research year, but that is hugely important within this relatively small community. you have the opportunity to demonstrate hard work ethic, resourcefulness, and problem solving and work directly with an academic ortho attending. compare that to a gen surg intern year, where you will be worked hard but will be evaluated by gen surg attendings. not to say that ortho attendings don't value gen surg evaluations, but they are two very different fields, and they likely will have no idea who that gen surgeon is. furthermore, as an intern you are mostly working with your senior residents. I haven't personally heard of anyone in the last year or two doing prelim then matching, although I'm sure they exist. but, I can say that I personally know a half dozen people who were poor candidates or didn't match, then were able to match after their research years.