Good discussion everyone and agree that if you are doing a research year only to boost your derm application that's not a great idea and you might become unhappy. By the way, research does not equal pipetting in a dish. There are other kinds of research such as chart reviews, epidemiological work, etc. that can have significant progress in a summer and wrap up over MS2. When people compare to PhD, the vast majority are basic scientists (although some can be epidemiology PhDs too but this is much rarer), but there are other kinds of research out there.
Research greatly strengthens the application, by a lot, but only if 1) you have met the filters so that people actually look at your application (PhD tend to get an exemption though) and 2) you come across as genuine. If I had to rank what gets your application looked at AND called for an interview, the first pass is Step 1...if you don't do well, you may get filtered out by a computer algorithm whether you think that is fair or not. Your clinical grades are very important and having AOA status really boosts your application. Then it comes down to the individual that reads your application. Seems like a lot of people focus on (in no particular order): the letters of recommendation (by reading between the lines on the letters), your research, and the personal statement (some faculty read this closely although not everyone puts as much weight on it).
That said, if you do amazing on Step 1, are AOA, have none to a few research items, and have great letters of rec, you will likely get a lot of interviews and probably much above the "magic number" of ten or so. However, if you take that same person and put on a bunch of research publications that exhibit a drive for research and discovery, the interview count will go much higher. If you have a ton of research and don't do well on Step 1 and grades (as asmallchild points out), you're gonna be out of luck because research does not trump good grades nor does it trump not getting a good enough step 1 to get through the filters. Again, PhDs typically are an exception and get a pass on things like step 1 filters if their research is intriguing.
Remember, dedicated research also develops connections and connections are the true king/queen for derm applications.
All of the people that I know personally that got 25+ interviews had a lot of research and did take a year off, interestingly were NOT PhDs, did amazing on step 1 and on clinical grades (although one of them was not AOA), and were charming people. Bascially a rockstar. These people have appeal to both clinical and research based programs. My point is rockstars have research and typically have dedicated time for it...on the flip side you do not need to be a rockstar to match into dermatology.