Don't forget to consider the power factor and that for a receiver the (true) watts will be different (lower) than the required VA (apparent watts) rating of a UPS. I don't know if E* has already taken this into account.
My 622 says it draws 120 Watts. Whatever. I use an APC 1000VA UPS with voltage regulation and spike protection. I also have my Samsung DLP set plugged into the UPS because we have frequent short-term power outages. My 622 and HDTV never blink when we have short-term outages. Also, my DLP set has a fan to cool the bulb after shutdown, so I don't want the fan to quit immediately when the power goes out.
The power surge that can come when the the local power lines go off and on is never good for any electronics. So, I have another 600VA UPS on my DVR 510. I once recorded a couple of shows on it using the UPS for power until the AC power came back on. And of course, there is a UPS on each of my desktop computers.
With the freezing rain and sleet we have been having in NE Texas, I bought a big deep-cycle marine battery (with wing-nuts) and a couple of DC to AC inverters. A few years back, the power was off for 10 days. I had a marine battery but used it for a camping light and a 5-inch B&W TV for VHF.
I have not done the math, but figure I can run the 622 (or maybe better off to run the DVR510 at 50 watts) on the marine battery for a long time if the power goes out. I run the TV out coax on the 510 to a handheld color TV that runs on batteries or AC. One day I will put an amp meter in the line and do the math on how long the DVR 510 or 622 should run on the big marine battery. Actually, I have two of them. No boat, just batteries.