That matches my experience John; I listened to the DD-15s and also heard a couple of the new models at CEDIA ; Excellent voice match to the M- speakers I thought;

If M- hadn't come up with the new models solving the bottom end issues, I would've opted for Velodyne, M&K, REL in that order;

any of these choices would be good from my seat. For those looking, make sure not to count out the M- subs based on passed performance - these new models resolved many of the issues, bringing them into the decision process now...

ken