I'm currently in my junior year, doing CS and math double major. For the next year, I have the choice of spending a semester abroad at a top 20 CS program. I have completed nearly all of my required courses, except one.
The thing is that, if I cannot take an equivalent of that course in the semester abroad, I won't be able to graduate at the end of four years, I will need an extra semester just to take that.
On the positive side, in the semester abroad, since I do not have much course requirements, I will be able to spend time doing research (the school I will be going has undergrad research program).
So, my question is, how much one extra semester (probably with only one course in it) would affect my chances in graduate school admissions (for US)?
Note: I know that the extra semester would cost me a whole year due to the admission cycles. In that semester, I can stay at my current home instution (maybe again working with a professor), because double major students are allowed/expected to complete in 5 years.