The DirecTiVo (HRT22?) integrates into the DTV system just like any other DTV box. In fact, the hardware is an OLDER DTV DVR. The difference is in the software. The interface is the old familiar TiVo interface.
Oh yeah, please note that the new DirecTiVo is OLD Series 3 platform and interface (not the Premiere HD new and improved interface) has virtually NONE of the retail TiVo features such as MRV, OTT (Netflix, Hulu, Amazon, etc.), and I forget what else it doesn't have compared to the retail boxes, and it won't work with any of the coming TiVo products such as the "extender" technology (essentially straming to another room using a small device for that purpose only and not require a complete TiVo set-top-box, so some money saving there).
In short, the DirecTiVo is a neutered OLD box and platform that provides pretty much ONLY the OLD TiVo interface. This is a box for TiVo lovers who must have the old familiar interface.
Now, if it were a Series 4 platform with the improved HD interface and AT LEAST allowed MRV, then it would be something for more people. It is a sad story.