Here are my thoughts on this issue:
First of all, 4 weeks is way too short to do any meaningful bench research. So if you were to go into a lab, you would want to be close in order to finish up any loose ends during your 2nd year. Going away to another school won't allow you to do that.
So that leaves you with research at your school. I really think that research is a binary issue during application season; the PDs see if you have done any or not. If you have a paper or two, then a checkmark goes in the box for research. I can't be absolutely sure, but I would bet that 5 papers is the same as 2. It's research. Unless you are patenting some new artificial bone matrix, research is research. You put in your time, work hard, publish (or sometimes not) and you get the checkmark.
That said, this the last 4 week break you will have for the rest of your life. You aren't going to take a month off in residency. When you work in the real world you certainly won't be taking time off like that.
Since I really think research is research, consider doing something else that could potentially differentiate you from another applicant. If you can still get some good research going during 2nd year (which you absolutely can), then you'll have the checkmark. Go do something cool during the summer, like work on an Indian reservation in a clinic for a month, or do some other kind of humanitarian work. Build houses with Habitat, travel in Asia, do anything other than research.
In a sea of applicants who did research, you don't stand out by doing research. That just keeps you in the hunt, and it is something that is easily achieved during the school year. Your application is your opportunity to market yourself to these schools, so do something that will catch their eye and give them reason to invite you for an interview to find out more.
I had plenty of research, but I was asked way more questions about my non-academic life than my academic life.
