Time for an update:
Still very little demand, we don't have it.
After months of negotiations and internal roadblocks and rule changes, we got caught in an end-of-fiscal year freeze. No Comcast Gigabit Ethernet Private Line WAN until sometime in early 2011.
Too bad. We had pulled extra cabling through conduit for that connection, so it would survive construction. Stuck with only 45 Mbps until then.
Headquarters made us an offer we couldn't refuse, so we went with Avaya VOIP. If that doesn't work out (another site has had multiple multi-hour outages), we will re-consider Comcast phone lines.
We dumped DSL, pulled coax from the Comcast MPOE to our telecom closet, and installed Comcast Business Class Internet. Our visitors network has been faster and more reliable for several months now. I'm happy :-)