In my trials of the Sarpo varieties, before they were released to the public, I noted that Mira got a small amount of July blight, but it got over it and continued to grow. I found that Axona was more resistant to July blight, but I did run into August blight problems last year for the first time.
Yes, I know that blight was bad last year, but I suspect that there may be a new version of blight causing the problem.