I had a Slingbox before getting the Stream and for local Streaming it's 100x better. The Slingbox had a considerable lag between what was happening on the actual TiVo and what you were seeing on screen which made skipping the commercials very difficult. The Stream has direct control over the TiVo so even though it does have a tiny lag when skipping the skip is at least controlled and accurate. Also when the TiVo app reaches the end of a program it allows the iPad to fall asleep, which is nice for watching TV in bed. The Slingbox just plays forever and the app did not offer any sort of sleep timer so I'd end up waking up in the middle of the night to turn off my iPad.
I don't know how they'll do with external streaming, but if they can make it work as well as internal streaming I'll be very happy.
Developer for VideoReDo