From what I'm aware of, the Hammer dynamics is a refined approach to the LTA.
The PA system I built last year used several Emminence Beta 12 LTAs in open baffles. I had them tailored with active eqs but they were more than passable left alone. I even made a few phase plugs for them. REALLY helped. I'll be trying them in my Beulah cabinet in some time, so I'll have to let you know how they turn out!
My feedback overall? definitely worth $60 bucks a pop! play play play, try different drivers. Its all a matter of taste in the big fullrangers.
Cheers,
-Clark