From my research, "boiling" is never the preferred method. Holding it around 150-160 for 10 minutes or so would be ok, but boiling sets pectins as stated previously, making for hazy beer. In secondary, the beer is no longer as hospitable of an environment for bacteria growth. Freezing often will kill off bacteria, breaks cell walls to make sugars more accessible. I have no need to change methods, it's working great for me. I often use a combination of frozen fruit and extracts to get a good pop of flavor in the beer. Fruit alone was a little lower fruit intensity for my liking.