savery,
One important thing you didn't mention. There are two important numbers to consider for an advanced DVR and backfeed to other TVs in the house.
1. How many TVs?
2. How many people?
In my case, there are four TVs but only two people in the house. A single ViP622 in single mode (most of the time) works fine for us because typically we are in the same room watching the same, be it OTA, satellite channel or DVR events. Plus it is more convenient with the DVR events, you don't have to be at a specific TV to watch. In modulator setup you can send both TV1 and TV2 signal to the remote TVs on different channels.
If there are more people in the house, chances are they want to watch different things so either run the receiver in dual mode with its inherent limitations (when recording on TV2, they can't change the channel but can watch recorded events) or use multiple receivers.
By the way my answer to the thread title Dish Network...Does it suck? Maybe, but for different reasons than dual-output receivers.