I got my frequency response chart. VERY nice, smooth extension throughout the midrange, and the usual LCD2 response in the upper-midrange. Very nice sounding headphones any day, and much better than any other headphone that I have ever used. The only headphones that I own that arguably have a better "soundstage" are my Ultrasone Pro2500s.
But the sound on these has more tonal accuracy, especially with regards to a very flat bass and midrange response throughout the entire range. On the chart I see a slight dip (-2dB) starting at about 40Hz, and then a slight rise (+1db) around 30Hz, then ruler flat to 20Hz. I think this is pretty normal and will not affect the bass at all. I even did some tests on those frequencies, 24, 26, 28, 30, 32, 36, 40 just to see if there was anything different at all...and there was no palpable difference in the bass slam at these frequencies. That, and the bass response of any headphone is also very dependent upon the placement of the phones on the head as well. I find that I can change the response slightly by moving the cups forward or backward across my ears.
I think the LCD3s do sound slightly better, having heard them, but I prefer the darker signature of the LCD2s for my ears. I prefer less treble. Either of these are good for basic mixing of audio for most situations, since they're ruler flat in their response right out to the upper midrange. They get the critical sound and tone right, which is what matters. Treble definition is still very much there, even if it looks rolled off on the chart.