retracted, i misread the above post
but ill add:
Comcast Tier 3 Tech is pathetic, Tier 2 is decent..... Tier 1, forget about even talking to them.... have to pay 99$ just to even ASK!!
few months ago, Routing tables for SE Corridor were corrupted. i was trying to reach a server in Chicago from Atlanta GA, get this: my signal, as verified by TRACERT and ping plotter would go, from Conyers, GA to Marietta, then Atlanta, then to LVL3 Atlanta, then ................wait for it..................................
Comcast's Regional "IBONE" backbone, to .....................
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MIAMI FLORIDA!! but that's the start.................
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then BACK to Atlanta, then to LVL3 Kansas City.... then off to Chicago. i had a poop fit with that....... latency for my gaming and a couple other latency critical applications went from a average of 18-28 ms from ATL to CHI to 80-150ms with severe spikes in to 1000+ ms !!!!!!!
then it got worse.......... i found out, through ping plotter and TRACERT, Comcast was also offloading my 120/20 Service ( yes, i have 120 Mbit down / 20 Mbit Up ) to POTS DSL Nodes for ATT? <-- DO WHAT?!?!? no POTS DSL Node can handle a 120/20 connection...... even VDSL wont touch that! VDSL will spike @ about 54/8 Mbps so effectively my service was routinely being cut in half by the offloading!!! this upset me and my house mates!! because we have a TON of devices..... 3 ipads, 4 PC's, 3 laptops, 6 android phones, and 2 more tablets, not to mention the smart TV's and a DVR for house cams..... ALL tied into the 120/20 service, QoS is enabled of course and manages well. that's being provided by a nOS "smoothwall" legacy PC i built. a P-III 933 1GB SDRAM 80GB IDE dual Gbit NIC system as the router, which feeds a WiFi N300 AP and then the 8-14 ports on Ethernet routed around the house.
it took me14 times of calls and emails to argue with Tier 3, Tier 2, EXECUTIVE CS !!! even the damn Engineering Supervisors !!! to get them to figure out there really was a Routing Tables corruption present. they wound up giving me a job offering ( which a heavy heart "declined" was given for personal reasons NOT relating to Comcast ) and 3 months no pay service.
Are they going to pay or give you a price break on there service for being a hotspot ?
no they will not, because it is their device already. it is NOT using your bandwidth to be reimbursed for, nor is it even tied into your account.
its related to this:
http://en.wikipedia.org/wiki/Multimedia_over_Coax_Alliance
EDIT 3 : reading the OP's post..... i spotted this:
"But what if you hate the idea of your private boxes turned into public hotspots? You can turn it off by calling Comcast or logging into your account online. The company says fewer than 1% of customers have done that so far." utter lie
Tier 2 line man that i had a nice chat with said it CANNOT be turned off. its embedded in the firmware