PSIP data is not equal to Electronic Program Guide Data.
No, but the ATSC tuner in the HR20 relies on a "replacement" PSIP data, if you will, to determine channel mapping. It gets that data from the satellite stream.
In other words, if UHF frequency 24 in "Anytown USA" contains digital channels 2-1, 2-2, and 2-3, a "normal" ATSC tuner scans the band and finds a modulated carrier on UHF frequency 24, it then picks up the PSIP data from that signal to determine what channels are on it and what to call them, e.g. "2-1 WPIG-DT" and "2-2 WPIG-24/7 weather" etc., as well as some other information about these channels.
By contrast, the tuner in the HR20 gets this channel mapping information from the satellite stream.
DirecTV gets it from Tribune (the same company from which they get their guide data), Tribune gets it from God-only-knows-where (but ultimately, it must come from the station itself, at some point).
The "chain of information" in this case is fragile. Lots of chances for human error to screw up the data.
Having a manual scan capability on the HR20 could "fix" problems introduced by human error. As I said before, the HR10 has such a manual scan function. Others have reported that the H10 and H20 do as well.