Just one caveat I’ve run into. A lot of the existing routers can’t handle a 50Mbps incoming signal. I have a 50Mbps account with a SonicWALL TZ 180e 25U. The ports are 100Mbps but the throughput is limited to 20Mbps. So you can get all this speed but it doesn’t do you any good if the equipment in-between can’t accept it.
And another little gotcha that some people might not be aware of regarding network speeds. My Dell notebook has some sophisticated power saving software, including one feature that lowers power to the network adapter while on battery. That negotiated the connection to 10Mbps and made me scratch my head for quite a while.
If you’re obsessed with getting the highest speeds that Comcast can offer, you may wind up replacing other equipment in your home or office before you experience all the speed you’re paying for. You might need a new firewall/router, a new 802.11n wireless access point, new gigabit switches, or new Cat5e/Cat6 cables. Speed is fun and might be valuable for your business, but it doesn’t necessarily come cheaply.
Oh, and keep an eye on that power-saving software for the network adapter if you’ve got a Dell notebook. I found it was completely disabling my network adapter at odd moments, with no notice. It made me want to hurt people. Here’s some more information about that.