I don't have it myself but I've observed many plants of iit over the years. Here it tends to have substantial black spot at first and then become fairly resistant as a mature plant. I don't know if that will happen in your case. Since it is hardy in your zone, it will survive even if it defoliates the first year. It does have a good plant habit, attractive foliage, pretty flowers, and good repeat.

I've had Bonica for quite awhile. I've found that the source of the plant DOES make a difference. I got one at our Botanic Garden plant sale and the other at Safeway. Both looked the same when I got them. After 6 years the Safeway one is a lot less vigorous with a lot of dieback. I've had no problems of any sort. I spray with lime sulfur once a year in December for black spot control.

jill