The HR22 and HR23 are the latest which are generally available (there is also a HR24 which should be generally available in a month or so). The HR22 and 23 have a 500 GB hard drive, but no internal OTA tuner (they will work with the AM21 external tuner). The difference between them is that the HR23 has a wideband tuner and doesn't require BBCs for non-SWM use (which isn't a big deal since SWM installations appear to be the standard now). They are a bit slower than the HR20. The HR24 is much faster than any of the current DVRs, has built-in DECA networking for MRV and will probably soon be the only one in production.
Also, the newer receivers are black instead of silver.
