With a single tuner box (600 and 605) you can only watch one channel at a time. Currently there are rumours that the pvr capability will be added to the 605, but when is anybody's guess.
The 630 is dual tuner pvr. You can record two channels while watching a third from the HDD.
You are limited to watching and externally recording that smae channel.
Shaw Direct DVR830 / DVR 605/ 605, Sony Xbr65" 950E", Sony XBR4 850d, Oppo 980H, Yamaha 7.1 Surround, PS4! WDLive