Small companies DON'T make their own cable boxes --
For that matter BIG cable companies don't make their own boxes!
If you do a search on the web you'll find that there is a small number of big companies that manufacture cable boxes (Jerrold, Scientific Atlanta, General Instruments, Tocom, Pioneer, and Zenith); as far as I know, General Instruments, Scientific Atlanta, and Pioneer are the only ones making digital boxes.
Replay supports all the boxes -- if there is a new box or one they missed that they DON'T support, let Tech Support know about it -- and they will fix it so that they DO support it.
There are tips and tricks to setting the boxes up to "channel surf" well; read the FAQ at the top of the page!
Ciao
Joe