Rsmith, why do you ask? Realize you can't buy the 922 anymore. So it's kind of a moot point. In any case, hopper is better in every way (more tuners, more space, faster, less bugs, PTAT, expandable). But hopper is missing OTA at the moment, and sling is now external.
Screds, you have a couple of options. Like you I had a single 722 that I replaced with a single Hopper, so my bill went up $4. But I gained an additional tuner, better/faster interface, better remote, PTAT, and a lot more recording space. And the energy cost is $1/month less, so net cost is only $3. So it was worth it to me for the additional capabilities/features. Instead of an analog wireless video sender like you have, I upgraded to an HD one which sends a perfect HD picture digitally to my other TV over wireless N. It works beautifully. It's an Actiontec MyWirelessTV. I got mine used for around $60 (new ones are $200).
If you get a Joey, that's another $7 as you already know, but eliminates the video sender and gives you completely independent viewing on the second TV. And the initial equipment is zero, unlike the video sender. That would be nice to have but wasn't worth it in my case since my second TV is rarely used and I found a good sender cheap.