The sling adapter is quite the different device than the sling box products. What was a complete surprise to me after connecting it to my 722K was the fact that it took control away from my DVR without warning and allowed me to watch the channel I wanted from a remote computer. Once I disconnected the computer connection as in closed the browser my 722K would return to a partial dual tuner device, maintaining dual mode until I reset it from the DVR mode button. If you are a prolific DVR user and have multiple tuners in use doing simultaneous recordings as I do, this SA will greatly restrict your DVR practice.
The traditional Sling Box does not work this way at all. It does not take control of your DVR, rather all it does is monitor the device output much the same way as your local monitor and sound system but sent those media signals to the internet. While you still have to access one tuner to watch a channel, at least with the box, you will get the same warnings as you would at home if you have both tuners in recording at the time. You have the same options as at home to shut down a recording and switch channels, or just continue to watch the channel in use for the recording. In effect, Sling Box, keeps YOU in control, while Sling Adapter, takes control and hides the disruptions to your intended recording schedule. THis assumes everything works as intended. Presently, there seems to be some bugs in the 722K implementation that should get resolved with a firmware update in the near future.
If you decide to get a Sling Adapter as opposed to the Sling Box, you should be aware of these limitations to the device. If your use is occasional DVR recording, rarely recording from two tuners at the same time, the Sling Adapter will give you a nice $150 cost savings over the box, but you will give up control and features of the dual tuner DVR in the process. If you are a heavy DVR practitioner, you'll be much happier biting the bullet and spending for the sling box. IN my opinion, the Sling technology is cheap either way to have your TV content remote assuming you have adequate internet speed.