I still have my TiVos because their software makes the 622 interface look antiquated. There is just no comparison on the features. Some of the season pass features can be done on the Dish DVRs but it is less intuitive. The search by keyword feature is not as good either.
Having said that, the 622 has multiple HD receivers and I can record 2 HD shows whilst watching another pre-recorded show. SD content is good quality too. The interface takes some getting used to though and I miss the TiVo ease of use combined with its powerful features. No 'togo' functionality on dish DVRs either.
So, I still have one TiVo hooked up to a single tuner SD receiver upstairs and I currently have the other TiVo hooked up to the 622. However this is going to have to change because:
1) I wanted to hook up the TiVo to the second 622 SD output & have it control the second tuner....but it cant baucause this would need UHF control.
2) Then I hooked it up so it could control in single mode using IR....however then it just started recording Dish's screen saver all the time. There is no way to turn off the screen saver, I even tried setting the 622 to auto tune every few hours. Doesn't work.
My solution, just get a single tuner SD receiver for each TiVo, and get the 622 for watching/recording HD. You can pick up single tuner SD receivers pretty cheap.