TiVo notes that the newest HD TiVo's (Premiere 4 and Premiere XL4) aren't compatible with OTA. They feature four QAM tuners and no OTA tuners. The Premiere still handles OTA but it is questionable how much longer it will be offered.
The Channel Master (Echostar) has two tuners.
I was recommending the HD TiVo , not the Premiere.
I have 2 TiVo series 3 Model TCD662160's with the original HDD's repalced by 1TB WD DVR drives - 142 Hrs HD, 1241 hrs SD capacity, both together cost me less than $600 including the special DVR hard drives.
I do not even look at the Premiere Line, Series 4, but all but the latest Premiere 4 do have OTA capability, that is something you need to watch with buying a TiVo - read the fine print and make sure the unit you buy is OTA capable.