I hav seen him fight a few times and I bet TD has also as he follows the sweet science as well.
Best pound for pound? I really dont know, some might think so, but its so hard to judge that claim, so many fighters claim the same thing. My favorite is Oscar De La Hoya he has had a rough couple of years but his last fight shut up most of his doubters, hes one of the greatest of all time. I hope Tito gives a rematch.
As far a beating Tszyu, there are a few people that I would like to see him fight, Arturo Gatti, Zab Judah, Jessie "James" Leija, and maybe Micky Ward.
In my opinion those are the best fighters in his weight class (140 lbs) But the best bet to beat him in my opinion would be Zab Judah.