As Pennstate, you are more likely to divorce if you have lived together prior to marriage. I wonder what the statistics would be if the timeframe were limited to perhaps a year. The reasoning being that once you get through the adjustment period, I sincerely doubt that the fact that you have lived together would have an impact on your relationship after, say, five years of marriage. At that point, there's something else going on, obviously.
My wife and I lived together before getting married. We lived together for about two years (engaged one of those) and then have been married for 2 years this May. Living together and marriage ARE NOT THE SAME THING. To tell the truth, we are both still adjusting to married life, in the sense of communal property and such -- much less so now. It's quite an adjustment, at least it was for me. It has been for my wife, too, since she was an only child (hence, no brothers to share with, like me).
In short, living together even for two years did not prepare us for marriage to any great degree. There was a period when we first moved in together that we came extremely close to breaking up because having someone around 24/7 was a first for both of us. I retreated to the computer when I needed to hide for awhile. It worked until we became more accustomed to no privacy.
Oh, as for living in sin, the question we were asked by the priest before we were married was "Are you living together as brother and sister, or husband and wife?" My wife's classic response? "Well, we have two bedrooms..." LMAO!! I gaped at her in astonishment, but that was DAMN funny when it happened.
I don't regret living together beforehand because it was the only way we could be in the same city (financial reasons). Given a second chance, I am not entirely sure I would do it again though.