Is an old Nautilus HTM1 worth adding to my system?

I currently have a set of B&W 683's and the smaller of the two 600 series center channel speakers. I'm building new system with Onkyo 818 reciever and have been looking to upgrade center channel. I have the opportunity to purchase a used but in great shape and working Nautilus HTM1 center. Is it worth the upgrade at 1K$ or should I look into just purchasing the HTm61 center? Or what I would really like to get is one floor standing 684 as the center. TV will be mounted on wall. Thanks for any input