important: Concurrent Annual RetractionIf you are holding both DF and DF.PR.A, you can redeem both classes of shares for whatever the unit NAV happens to be at the close of August 31. This is known as the Annual Concurrent Retraction Right.
For most brokers, there is still time to purchase both classes of shares and then call your broker and redeem your shares. The deadline for giving instructions for many of the brokers is the morning of August 1st. You should however, make sure of the deadline set by your broker. Also, you may have to wait two days after any purchase for the shares to settle before your broker accepts your request.
Interestingly, both classes of shares are still trading below their NAV. The only risk I can see is that you are at the mercy of the markets, so the NAV could drop by the end of August.