I’m with @audiotroy on his take of the AMT vs the upper frequencies of the DI.
Like Vitop, I am a fan of the AMT ribbons and based on my memory (I have not done a head to head comparison with the DIs) I find the AMTs to be ’brighter,’ sweeter, airier, and more extended than the DIs implementation of the tweeter.
To me, the DI’s upper frequencies (being less so than what I mention directly above) are therefore closer to neutral, BUT given the differential, I would also describe them as ’warmer’ THAN vs the AMT ribbon (at least the implementations I’ve heard). Therefore, I can understand why Dave describes the DIs as being ’warmer.’ To me this is actually a compliment.
I think Eric’s design makes for a much tougher separation between the mids and the high frequencies because of his tweeter array...which is a really, really, really, really good thing. : )