Ok, so let's see if I've got this all so I can explain to my wife in terms she'll understand why we're going to be changing our current "His 722/her 622" setup
The Hopper will have 3 tuners. Each can record a separate show. You can get a second Hopper if you need, and they can "see" each other, effectively giving you a 6 tuner setup if you need (plus OTA, which is a concept she grasps just fine)
Joey's go on TVs and can view anything recorded on the Hopper, OR watch Live TV if a tuner is available. (She'll love that since it means we can watch any show "from either DVR" in the sunroom on nice days, since the concept of "his & her" DVRs goes away).
In addition, if you have the "Prime Time Anytime" feature enabled, ALL the prime time programming from the big networks is recorded for a week (presumably this means that, for instance, last Monday's shows get overwritten when this Monday's shows are recorded); if you want to save a network primetime show it's copied to the regular storage partition before being overwritten (and as others have said, hopefully this becomes something that happens automatically -- it would be nice if I had timers set up for 2 primetime shows, and PrimeTime Anytime enabled, that it just automatically copied those two shows off the Anytime partition after they're captured)