My position is this:
Firstly, don't preach to anyone cause it gets you nowhere fast.
If a mormon were to come up to me and ask me about my faith? I would tell them.
If they wanted to debate I would tell them that there is no debate and they are incorrect. I would use the bible and only the bible to prove my points and then be done.
The Great Commission tells us that firstly we should help the person who has never had the chance to hear the Word of God. To me a mormon is not an unbeliever, but is a mixed up believer. I am not saying that they are saved, but the Great Commission does not tell us whatsoever to worry about people's salvation, that is for God alone and He doesn't worry.
To be blunt again...it's not our commission to convert people or is it to argue points to others about the Word of God....we do enough of that to each other(orthodox christianity)!!!
Why would I waste the time trying to convince a Mormon that they are wrong about things when I can be teaching a person who's never heard of Jesus what He's all about?
thanks for listening.