I've never driven a 4WD or AWD vehicle to any extent, so I'm only asking this out of common sense (which sometimes agrees with reality, and sometimes doesn't), but isn't the limiting factor in a panic stop (with or without ABS) the breakaway force of the tires to pavement, so for purposes of answering the question of which can stop quicker, as long as either the brakes by themselves or the brakes with the braking effect of the engine can cause all four tires to reach the breakaway point, the stopping time will be the same, everythng else (weight and weight distribution) being equal?
Bill Putney (to reply by e-mail, replace the last letter of the alphabet in my address with "x")