Heather,
I agree with your premise that no matter the history or background, God, in His Sovereign election and calling can reform, transform and conform us to the image of His dear Son. My personal testimony is all about His wooing, His patience, His Providential preservation though I remained an alien and enemy; yet He loved me and while still a sinner, died for me!
Much like Michael, I once thought those coming out of "unchurched" backgrounds had a more passionate expression of gratitude for salvation. However, as I progress in my journey with Him, I encounter those who know the amazing love of our Lord, the expense of displaying that love for us, and have an experiential knowledge of His Supreme grace at work THEN and NOW. We are from every tribe, kindred, tongue and a myriad of messy life situations and choices. Praise God for His indescribable gift of Jesus Christ!