Personally I haven't done it, but I do know few people who got into U of A med school after completing a study abroad program.
The only minus is you'll have to miss a year out of school. And depending how you'll look at it, it's not much of a minus after all, since you were doing productive school work in foreign country anyway, such as immersing yourself into new culture and language. If you'll know how to present it right, that actually can become a great advantage during an interview, since that will set you aside from other prospective students.
Anyways, doing a study abroad for the whole year is one-of-a-kind experience, and trust me, DO IT, if you have this opportunity. After undergrad school, chances of visiting foreign countries as a student would largely diminish.
I haven't met a single student yet who regretted going through a study abroad problem!
I hope my little message was a bit of a help and encouragement to you...
Good luck!
Crazy Cozak