I agree. It is not only a matter of his plans or not plans with a possible marriage, there are cultural differences and ways of approaching life.
This can be a good thing in a marriage, but if so all cards have to be layed on the table to start with, and many common decisions have to be made between the two people involved. Before a marriage.
Also history have to be clear, does he have children, have he been married before, what does his family expect of you ( in most cases you get married to a family, that expects things from you before and even after a marriage - mainly money ).
So once again, I know I am repeating myself and also other posters, live with the guy without getting married, try it out. If you plan to live here with him do it when you know how it is in all senses, the everyday life, the family, the financial part of the life etc etc.
Then, if you feel good about it, get your residency, cedula, get married and live happily. You lose nothing by waiting a few months to make sure this is right for you.
Why the rush to come down and get married? If you are worried he might go somewhere else, then this is not a healthy choice, and if he is of the type that goes somewhere else, he will do it, married or not.
Go easy girl, we have one life only that we know of!