Perhaps I should of left my post at my opinion to save from such an unfounded retaliation post. I would never consider the DT880 to be metallic sounding, I would reserve that for aggressive, harder hitting phones like Grado's or possibly the Sony SA5000 and HD800. I do enjoy a good transient response and find the DT880s to be spot on for me, the T1s a little more rounded, perhaps similar to the HD650 in that regard. So if indeed you consider the DT880s to be hard compared to the T1, I would consider the T1s to be rounded. It might even be a case that the T1 is much more forgiving with music, with their theatrical sound and softer treble they may well suit more people.
Flabby bass? are we talking about the same headphone here? One of the reasons I didn't like the T1 was because I found the bass to be a little louder, say +2dB, perhaps closer to the DT990 than the 880. I would not consider a T1 to be anything like a HD800, in fact I would go as far to say the bass of the DT880/600 is much closer to the HD800 than the T1.
Again, exactly like this.
I'm not sure what you're hearing and/or what you've convinced yourself of, but simply put the T1s are not everyones cup of tea, more of a side step than an automatic upgrade.