Love your quilt! But I think you will be much happier in the long run if you use all three borders around the outer edge. Continue your narrow green/beige/narrow green. Otherwise your quilt will look "chopped." just my opinion, after my own experience, I prefer wider borders, and love triple borders. Remember, the edge is where the hands have most contact with your piece of art: folding, smoothing, re-arranging, lifting... where the wear and tear will be greatest. Adding additional borders gives you something to revise, remove, replace after 20 to 30 years of loving wear.