I used Messenger every 3 weeks last year on my garden. The one big thing I noticed was that I didn't have much problem with disease. I had one bout with BS but it was short lived and did minimal damage/defoliation of the bushes. I think I can attribute this to the addition of Messenger helping my roses resist the BS to a better degree. I really didn't see much difference in bloom production or size of bloom that some have claimed to have seen on their roses. One other good thing from last year is that I didn't lose a single bush to old man winter here in zone 5 with no protection except what oak leaves fell from my two large trees in the fall and gathered around the base of the bushes.
I don't know if it was pure luck or that the bushes were stronger headed into winter this year compared to years past.I am going to use it again this year and see if I get the same disease resistance and lack of winterkill as last year.
John