I currently own both the non-USA Be-718s with the beryllium tweeter, and the DMD tweetered 718s with the GR Research crossovers. They are both driven by Wyred 4 Sound amps. The two systems are in different rooms - the rooms have quite different acoustic signatures.
To my ears the Beryllium tweeters are sweeter, smoother, but have less detail. They work better in my living room, which has reflective surfaces (one wall is glass doors), is open on one side to a kitchen, and is primarily used for listening to music. The DMD tweeters do more of the things audiophiles seem to like - sharper imaging, more detail. I use them in a smaller, better damped room, which is a den/home theatre. For dialogue in movies they are definitely preferable - the extra clarity is welcome. With both sets of speakers I also use REL subs - excellent integration and only fleshes out the sound all the more.
The crossovers, which I hoped would improve definition in the midrange and bass, seem to make little difference. I doubt I would be able to tell the diffence in these frequencies if listening "blind" to the US vs nonUS versions. Perhaps they are influencing the high frequencies too - with the results mentioned above.
I would add that the dedicated Usher speaker stands made a big difference. Across the frequency range they brought added definition and punch, with no negatives. Previously I used 30+ kilogram steel/sand weigthed stands with bituminous dots between speaker and top plate. Also experimented with cinder blocks and heights. The Usher stands are beautifully put together and actually made the difference between a good speaker and one that I find fully satisfying.
Hope this is helpful.
I purchased the DMD Be718s, the GR crossovers, and the two sets of stands from KCAudio (hifi223)- his service was excellent!
Cheers, Rob.