I agree on the yields and think the Canaccord pref are in the same boat and their balance sheet is mostly cash that exceeds the preferred outstanding at par!
I'm sure you know this sculpin but for the benefit of the thread, I believe the DC.PR.D are better than the DC.PR.B if your holding period is to the reset date of September 2019 (or longer) as the issues are interconvertible at every reset date. If you factor in the capital gains on the D's (all else being equal) you get an overall return that exceeds the B's by a couple percent and its a little more tax efficient.