I am using a Harmony 688 with my ViP 622 DVR. Works fine, for the most part. No compatibility issues, it does every function that the original remote does (plus runs all my other gear, too). I use AAA rechargeable batteries, one set in the remote, one set in the charger, no issues there. I'm not a big fan of the buttons, though. they're the rubbery style, and they are definitely showing signs of wear. In fact, the custom buttons that flank the LCD screen are in sad shape. the kids picked away at them, so one 1/2 is missing, the other 1/2 is pretty ragged. Once these fail completely, the remote won't work any more (no way to access the DVR screen, for example), so I'll probably replace this with a newer Harmony. If you already have the 688 or plan to get it for under $50, go for it. But, if you're planning to buy and spend over $50, I'd look at another model with better buttons