I'm assuming you mean the Mini Dancer One. Don't look at the power ratings. They can handle plenty of power. 250W is a very nice match for the Mini Dancer One. In my opinion, it is a superior speaker to the BE-718, but the improvements are certainly not dramatic. Since you already have the BE-718, I personally don't think it would be worthwhile to move up to the Mini Dancer One for the small improvements.
Disclosure: I am an Usher dealer
Disclosure: I am an Usher dealer