Just an update.
As I posted earlier, the activation process was relatively painless (for AT&T at least). Passed along the obligatory details (billing...address...etc). I got the modem 2 days later (April 25th). Which was fast for me...I would've expected a week or so. And the following Monday, the 28th, the tech called me up during work and advised me that everything was good to go.
Speed wise, it is just a bit slower than what my Road Runner gave me. Speedtest's website shows me having speeds of about 5.1 - 5.6, versus the 6.8 that I averaged with Time Warner. So be it.