Feet forward puts ALL YOUR WEIGHT on your ass, totures your lumbar region. Pegs under you helps support your weight with you big leg muscles. Forward controls are a hold over from the Easy Rider days... a fad the MoCo and others are trying to keep alive. For a cruiser, the holy grail is the "kitchen chair", knees at 90 degrees. Highway pegs are usefull for stretching the knees occasionally. (NOT for continual use on city streets where the brake is 1.5 seconds away)
This is me, 34 years ago, it hurts just to look at the picture now. I will NEVER, EVER ride a bike with forward controls again.