ReplayTV and Tivo came out at about the same time. Both were similarly priced, and ReplayTV also went to the low-unit cost and subscription model. (not just lifetime units)
TiVo did a much better job of marketing, but IMHO ReplayTV had a slightly better product. (I found the Tivo UI annoying and slow.)
The 4000 and 5000 units had automatic commercial skip, and the networks sued ReplayTV into bankruptcy. The final model had commercial skip disabled, but it was too late. Eventually the company was gutted and sold for parts/patents.
On 7/15/2015 DNNA (the final owner of the guide service) declared bankruptcy and guide service stopped (The community has found ways to provide guide data!) DirectTV still owns the patents and the name.
It will be interesting to see if Tivo is sued out of existence as well.