In a business setting reliability is a must (an absolute must). Go with T1, if you need more speed either get more lines or get a t3 or better line. DSL is highly unreliable and not suitable for anything more important than residential use.

T1 is dedicated bandwidth, the company pulls all the stops to make it more reliable than DSL. The point of T1 is not to have massive speed, but to have rock solid reliability on what you do have.

__________________