I do love people spitting bile about things they know nothing of, breakup at 24khz? I've never heard it and more to the point hifi choice completely disagree with you as do their tests , I believe the correct phrase you are looking for is 'lift' , also B&W diamond tweeters 'breakup' (your words) at 15khz not 50. See review (http://www.hi-fiworld.co.uk/index.php/loudspeakers/65-reviews/511-usher-dancer-mini-two.html)
Now the lies have been dealt , I have owned my BE718DMD for a while now, they are quite simply outstanding speakers , every time I change something in my system, good or bad , these speakers tell me exactly , speakers cables , source , interconnects, I can hear it .
If you like warmth stick with the BE , if you crave detail , soundstage and realism , the DMD is for you.