These things are still around...
Ran into this the other day, it immediately appealed to me to use the double-shielded RG-6 in my walls for my home networking. I already had a desktop in a bedroom that was connecting via wireless-n, and then I got a Roku box near my TV, and that was running marginally okay with 5.4GHz. wireless-n. But then I ran into these "media on coax" adapters on the internet, and decided to try them for my Roku box after reading the review here. They installed easily, worked great the first time out of the box, no configuration.
I measured the throughput (very roughly) by connecting a laptop to the TV end, and transferring a large file, about 8GB, from my desktop to the laptop. Came out to about 85Mb/s, I watched the transfer and the transfer rate looked very steady at that rate. It started a little faster, then leveled out and just stayed there. So I've now added a third adapter in the bedroom to replace the wireless-n there, easier and more reliable than wireless. That one is working very well, also, so I'm happy with these.
I've not been inspired enough yet to check the bandwidth by connecting a laptop to both remote adapters at the same time, and transferring 2 large files concurrently...the review leads me to believe that I should get a larger total transfer rate than just 85Mb/s, but I haven't had time to set it up.
So, no problems here, no configuration has been necessary, just plug-and-play. On the other hand, I live in a single-family home (not an apartment house), so I'm not too concerned with security (haven't set it up yet), and no satellite TV, so no problems there. It just seems to work. Security could be a concern, I'm not sure how much goes back up through the line, or if anyone cares *smile*, but it sure is nice to leverage all that coax in the walls. It isn't super-fast, but my broadband internet isn't that fast, either, and the two systems that I care about the transfer speed between both have Gb. network interfaces and are on Gb. router ports. So the transfer rate between those system is really good, about 25MB/s for an eSata backup, can't complain about that.