In the first 12 hours of it being on Kickstarter, it passed the halfway mark, pretty much guaranteeing its funding. What would you make with one of these if you had one, and how do you think this is going to change the Amateur Radio landscape?
Yep. The DOCSIS standards used in the US give you a little less than 40 Mbps downstream per physical 6 MHz channel. Higher-end DOCSIS 3 modems can bond up to eight channels together.
IIRC, your speed is artificially limited by the modem, which is configured remotely by your ISP over SNMP. People used to hack their cable modems to remove the bandwidth limits, but the cable companies started cracking down on them.
... but their Xfinity Wifi Hotspot program, if implemented correctly, shouldn't cause customers any real harm.
What I believe happens is that your modem gets virtualized into two modems/routers. Cable Internet is already based on shared broadcast signals, so in terms of bandwidth it should be identical to adding a second, mostly inactive cable modem somewhere in your neighborhood. Since the 2nd modem is virtualized, it should not affect your transfer rates or bandwidth quotas.
This second modem is connected to a second, virtual router, with its own SSID. Unless there's a vulnerability in the router (which is possible), users of the Xfinity Wifi Hotspot should not be able to access your network, use your IP address, etc.
Available bandwidth could conceivably be reduced, due to more packets in the air, but WiFi is already unregulated and subject to additional interference. Increased load on the modem/router could theoretically reduce your bandwidth as well, although probably not by any noticeable amount.
The best claim is based on increased electricity usage. However, the additional energy needed is probably negligible. Here is a link to a blog post about the increased electricity costs, where they conclude it's about $8 per year in the mid-Atlantic area -- if it's being used. Comcast could give everyone a $1/mo credit for enabling the Xfinity WiFi Hotspot, completely eliminating the issue.
It looks like they are trying to hide behind their EULA, which says that "Use of the Software as a driver for a component that is not a Genuine FTDI Component MAY IRRETRIEVABLY DAMAGE THAT COMPONENT." But there are reports that this new driver is being delivered via Windows Update, which presumably doesn't show you this EULA.
Microsoft would be wise to pull this update.
I believe there's some evidence that Comcast intercepts DNS traffic for non-Comcast IPs and redirects it to Comcast's DNS servers.
Also, I doubt it matters whether you use their DNS servers or not--they can inject traffic into any TCP stream.