I wonder why I'm not buying the extreme speeds they claim. I'm not sure. Maybe it's something to do with:
Speed rating: 12 megabits per second
Speed in real numbers: 1.5 mb/s
Real speed (relatively good): ~350 kb/s
Speed rating: 480 megabits per second
Speed in real numbers: 60 mb/s
Real speed (relatively good): ~4.5 mb/s
Speed rating: 5 gigabits per second
Speed in real numbers: 625 mb/s
Real speed (relatively good): 25 mb/s
You can get faster speeds from these ports--if your device can send at their high rates, you will get data that fast. Still, the type of storage devices that are most frequently used on these (not talking about backup hard drives that cost more) are not capable. Flash drives don't go anywhere near the speeds the ports should let them, and neither do SD cards. Just because the standard can support it won't make SD cards SSD speed. Even if it has been proven to work via someone actually building a prototype, no cards actually providing that functionality will become available.
Also, I'm guessing these "extremely fast" cards will have the same problem that affects current cards that are high speed and high capacity: they're great for storing lots of large files, but if you need to store a great many small ones, they become slow. No problem for a camera, especially those ones that take massive raw image files. No problem for my main use case, audio recorders that are frequently called upon to record for hours. But it is a problem for anything trying to run an operating system off one. Not many operating systems have files that are individually larger than about 128mb, but most do include lots of files hovering between 10 and 100 kb. For the SD card to run the OS, it will need to handle that well. Oh, by the way, do you think all those devices using SD cards will get off their addiction to FAT32, because we're already at the point where that file system isn't useful.