If I were to buy such an item, would it be necessary to have it's hard drive reformatted by Shaw?
Honestly I really couldn't say one way or the other as we do not supply or support these. I do know some people have set up recorders with success. You would connect the Shaw box into the recorder instead of the TV, then the recorder to the TV. The recorder will only be able to record the channel the Shaw digital box is on, so you wouldn't be able to set a recording and watch something else. Also passing the feed through another device could reduce the quality of your picture.
Your best option would be to stick with a Shaw PVR, and if you need more recording space, pick up an eSATA expander.
Retrieving data ...