I would expect them to be delicious as black Cavendish, as well as potent. I've kilned all the burley red tips that I had left. The kilned version makes top notch cigar filler. (I rolled a kilned burley red tip puro this morning, and wrapped it in the same. By the end of the cigar, I began sweating, felt queasy, and my insides began to rumble. It's using it as a wrapper that does that. Direct nicotine slam.) When wrapped in anything else, it's smooth as a baby's bottom.
John,
I've used black Cavendish as a dark wrapper. It works well. I would suggest not block pressing it, but just handling the leaf like any of your other wrapper leaf.
Bob