I've just upgraded from a DM8 to an NT and the difference is quite substantial. The way it shoots is pretty much the same as any DM I've fired, except that the trigger is really awesome (though the DM10 has the same trigger as the NT, and I think maybe the 9 does too?)
Most of the differences are making it user friendly for me. Comfort, the tool-less grips, bigger buttons on the back, the new feedneck, new airport, the new coloured o-rings, and its very small and light, however if you set it up right the consistency and efficiency can go way up from the old DM series.
Plus, if you get end up choosing the NT, BZ are currently doing a promotion where they throw in a virtue redefined board for an extra tenner (it's about £90 by itself) which is a very nice upgrade for it.