CDR's are great products however they generally should be considered by those who have a tighter time horizon or are possibly in/near retirement and don't plan on utilizing another currency other than the CAD.
A prime example of a benefit of a CDR would be a retiree who wants to benefit from owning Bank of America but doesn't travel much outside of Canada and thus doesn't want to be receiving investment profits and even more importantly dividends in USD. They'd have to exchange them to CAD which in the end would result in a lot of currency exchange fees.
In addition to this, they could be valuable to someone who has a shorter time horizon and who could open themselves up to currency risk in the event the dollar swings in a single direction. Over the long term, currency fluctuations tend to even out and by hedging against currency movements all you've really done is paid the bank a fee to protect you from something that in the end doesn't do much. However, if your time horizon is short, you may want that hedge so you don't get burnt if the CAD is 5,10, or even 15% stronger than when you bought.
If your time horizon is long and you have no need to spend the returns/dividends received from the companies, I don't see any reason why one would hold the CDR though. You'll pay 0.6% annually to hedge. Many are worried about the exchange fees at your brokerage, so they own in CAD instead. When in reality, you'll pay these fees pretty quickly just owning the CDR for a few years over buying USD and buying the USD stock.
Hope this helps.