I've got a replay and Dish at my house. It should work using the IR blaster to control the receiver but all the recordings will be in standard definition because the replay cannot do HD. For my setup I ended up getting the PVR from dish it's about 5 bucks more a month. The dish pvr has amazing picture quality compared to the replay because the dish pvr just copies the stream to the hard disk so the video does not need to be encoded. On thing that sucks about the dish pvr is menu/interface sucks.
I also hooked up my replay tv to one of my receives without a PVR. It works pretty well, the ir blaster is able to control the receiver. the only problem is that I'm having is that the dish will turn on this annoying screen saver every night. I think the dish receiver turns the screen saver on after it updates its onscreen channel listings every night. Any way?s its annoying because you have to hit select to dismiss the message and replay is unable to do that so a lot of times my replay will record a screen saver instead of my show.