T1 vs. Roadrunner Business Class?

We currently have Time Warner Business Class. We are being talked into a T1 for our phones with a separate T1 for our data lines. I have someone else telling me that the T1 would not be worth it because of the speed up and down is slower than cable. I am trying to find pros and cons but I am inundated with too much “technical” information that it is driving me crazy!!! Can anyone tell me why one is better than the other? Thanks!