I have. I had a guitar with a 12 hole tie block and tried tying with the traditional 6 hole method (which significantly reduced break angle). There's no detectable difference. Even individuals with a 6 hole tie block can test this by using the diamond string ties to mimic a 12 hole tie block. It is important to note that different tie blocks whether 12 or 6 hole can produce different break angles depending on how it was designed.
Even if there were a difference, it would hard to attribute it to anything more than placebo or string conditions, humidity conditions, etc. Even if you retie using the exact same strings but with a different method, strings that have been loosened and retightened will sound radically different and will take some time to settle again, and by the time they settle down there are other factors present that could affect the sound including the players memory and perception.
In short, it isn't significant enough a factor to make an impact on sound. One should choose 12 or 6 based on aesthetic or tying method preferences. Another important factor I am not entirely sure on yet is if increasing break angle makes the strings feel less compliant or more stiff.
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