The XS-650 is a fantastic in-boat speaker! However, it wonít keep pace with your 80ís. If you balance the output then youíve restrained the 80ís. The only upgrade to consider would be to stay in the tower speaker family with a Pro485 (3-some) or another pair of Pro80ís.
Hold out if necessary and do it right. Also, your optimum choice could be dictated by your current tower amplifier. Consider this as part of the equation.