Ok, IT gurus I need your help again.

I'm skeptical about switching over to Cable for our internet connection. It was suggested that we go with Comcast cable in order to increase our download speed. Here's a quote from another topic, but was never answered correctly.
"Given the state of "faster" broadband technologies (5 Mbps to 9 Mbps Cable) and Broadband "Business Services" catering to true business needs, etc., why would one decide to look for leased T1 connections versus, say, a business-class Cable connection? I'm looking for a pro/con list and a discussion over whether broadband can actually be considered a point-for-point replacement for a T1 in the business arena. I'm not seeing how the traditional T1 route can justify its costs any more. Maybe someone with a little more longevity in this industry or more WAN connectivity experience than I can weigh in on this.
Example: A medium-sized business needing true 24/7/365 connectivity, prividing online content to nation-wide customers. In a situation like this, things like uptime SLA's, static IP's, (possibly) hosted DNS servers, Cisco router/PIX connectivity and compatibility, etc. become true issues. Typically, a business like this might opt for the standard 1.544 Mbps T1 with a failover connection to a (gasp) ISDN 128k or something of that ilk. But why not go with redundant Cable connections now?
Other Issues:
Price?
Reliability?
Gauranteed throughput?
Multiple public IP addresses?
Customer Support turnaround times?
Supported WAN protocols?
Single points of failure?"
Now I've almost never had any problem with our T1 line which has been here for the past 7 years and worked perfectly. Any internet outages were on our part and aside from occasional lag (again on our part) our average bandwidth (SNMP installed and monitored on our router) is around 50k with spikes around 150k a second once or twice a day when someone is downloading from us. I found from Comcast they claim their connection is digital (one line, I'm guessing symmetrical Full duplex? no representative could give me a straight answer on that) no VOIP, shared connection depending on usage in our area, guarantee 8 down and 1 up. With their "powerboost" 16 down and 2 up (not guaranteed).
We're eventually looking to switch to VOIP as well as hosting our own email, we have FTP servers, and video conferencing. I've been recommended bonded T1's by at least 2 other friends who are network admins at other companies (much larger though). So, any suggestions or articles I can look to for advice? Thanks again everyone!