I used the Kent Tech M method, on 3 tanks, with 100% success. That was about 3 months ago. So far, no signs of Bryopsis. I will warn you that you'll notice some corals bleaching out. I saw bleaching, primarily in my Zoanthids, Turbinaria reinformis and 1 Pocillopora. The color will return though, but it will take awhile. Another advantage that I noticed; I had some stubborn turf algae that was also wiped out.
Another method, that's supposed to work quite well, IF you can remove the rock/corals from your aquarium, is to dip them in a CoralRx bath, for about 15 minutes. I did this, on a couple of frags, prior to using the Tech M. It took 3 baths, but it did kill the Bryopsis.