I ride butterfly bars, and have considered reversing them. I see two problems with it. First, your close-flat position will be angled outward, either forcing your wrists to turn in sharply, or forcing you to ride with your elbows out. Second, mounting your shifters and brakes onto the close-flat position will be difficult with most mountain-style brakes/shifters, which typically have to slide on from the end of the bar (and around every bend).
After experimentation, I have my bars mostly level front-to-back (front is slightly higher), and have the bars at about seat level. This works pretty well for long-distance riding comfort. For shorter rides, dropping the bars increases my average speed, but causes hand numbness after about 40-50 miles. YMMV.
Here's a profile to show the angle of my bars:
