I had a 68-inch, 60# Wesley Special with a carbon back. Very nice bow. Very smooth and quick. However, since most of my other bows were mild R/D 64-inch bows, it just felt too long to me. Also have a 66-inch, 55# Big 5. One wouldn't think two inches would be that big a difference, but the proportions seem to fit me like a glove. That's why I just ordered another 66 incher.
I agree that stack could become a problem as one goes to a shorter bow, particularly 64 or 62 inches. If I do that, I would drop down in weight. There may be more finger pinch, but at a lower weight, one is less likely to feel it. I didn't notice finger pinch or stack on the 48#, 64-inch Halfbreed that I so foolishly sold.