Well, It's been a while since I've thoroughly auditioned the T1s, but I do remember not liking them too much. The mids were neutral, the bass was well defined and very tight, but sort of lacked weight and the highs were too sharp and a bit uneven. I auditioned a few headphones in juxtaposition, as my friend is an employee at a hi-fi store, and thus I had access to an amazing array of headphones and sources. Funnily enough, the T1s were his favorite dynamic headphones and so he actually owned them. To each their own I suppose.
If I were to compare the t1 to the pro2900, I'd say that the pro2900 has smoother mids and highs, the bass is stronger and the soundstage is wider. Transparency and imaging on both is very good, but it's been a while, so I don't know which one is better in that regard. As for detailing, I definitely don't think either one is far more detailed, and to be honest, headphones don't need to get more detailed than the pro2900. It could very well be that the t1 is slightly more detailed; my custom iems, for one, are.
Once again, my memory of the T1 has faded with time, so I might be wrong. All I do distinctly remember is that I didn't like them too much...