"The $716 billion is only a projection of how Obamacare reduces the rate of growth in Medicare spending,"
Exactly. Newt Gingrich, when he was Speaker of the House, argued forcibly that cutting the rate of growth is NOT a cut. I guess Republicans believe that cutting the rate of growth is fiscally prudent if Republicans do it, and a cut if Democrats do it.
Besides, the savings come from stopping the overpayments to the Medicare Advantage Plans. The overpayments (begun in the Bush administration) were designed to lure private insurers into Medicare; it guarantees them 20% profits; without that guarantee, for-profit private insurers refused to enter the Medicare Advantage market. That's why both Obama and Ryan plan stop overpayments.