Timing a new Tivo purchase

I was ready to buy a new Tivo, but was wondering what the normal cycle of new models was. Seems like the Roamio has been out a while and a newer model might be coming soon.



Any ideas? Is it about 2 years between new models?



I bought a Tivo HD about a month before the Premiere came out, so I know what it is like to get burned by an new model.