My 522 has been running in this configuration since it's initial install in February. I have been struggling to convince them to install it correctly with both a sat 1 and sat 2 input. See thread below.
There are things you can't do with only 1 sat line to a 522.
1. Operate a second TV from your 522 with viewing that is independent of TV1 2. Watch 1 thing on TV1 and record a second item different from what you are watching.
If you already have a 522 and are happy with 1 TV output and watching and recording the same thing then this should work. It's a shame not to take advantage of the 522's more advanced functions though. Did the install call for only 1 wire to the back of your 522 or did the installer not realize that it required two inputs to get it's full function? I'm curious because I have had three different installer's tell me that 1 wire to the back of a 522 is the norm.
Mine does support TV1 for watching and recording the same thing with only 1 wire hooked to the back of it.