I would not be to complacent about I am just on my first TiVo box, in my case my TiVo box died after 3 years and I lost my recordings that I was saving to watch on it
As Spiderplant has said you can recover your series links and as there is a good chance you can catch them on various catch ups, the problem I had was not knowing what episode I was on for what series!
The tell tale things that should have told me my hard drive was slowly dying was, recordings skipping whole sections on playback and TiVo recovering all my deleted recording from trash