The author of the article is completely wrong about the expanded recording capacity as bhelton71 notes. The recording capacity is fixed at about 400GB and adding external storage is, was and will likely always be for archiving only. 400GB is enough to cover most situations, but if you are one of those who takes extended vacations, the HR2x's capability to record directly to external drives may be just the ticket.
The downer bullet point about guide information not being available for local channels contradicts itself. The beef should be that local guide information isn't free.
I'm not impressed by DIRECTV's "support" of external storage as it isn't well documented and DIRECTV has done very little to help customers discover and use it. It has been kind of a dirty little secret and if you want to use it, you pretty much need to find specifications, help and advice somewhere other than DIRECTV. It is not at all surprising that Bob and Lisa don't know that the feature is available and it sounds like Bob might be a good candidate.
The author also erred in stating that the ViP722 could record two programs at once. With the setup presented in the review, one can record three programs at once. A similar error appears in the HR21 review where it doesn't note that you can watch a recorded program and record two new ones simultaneously.
Again, the AM21 may well be another dirty little secret. It gets some press on the Digital Transition page of the DIRECTV website, but they're not going out of their way to educate customers on its utility or availability. DIRECTV has never offered a press release regarding availability of eSATA support nor the AM21.
