When one is on a debating team, one learns to listen for the opinions of other people before speaking one's own opinions. Skills such as listening and phrasing one's arguments in a positive light while still sticking to one's guns on certain topics is probably a good way to face disagreements that will arise in marriage.
I think that those who are willing to think critically, and defend their ideas, do better in relationships. Of course, an obnoxious person who is always right, or a person who is always compliant, both make less engaging spouses. But those who will debate with an open mind, even willing to defend a stance they don't personally espouse, would make better companions.