No I haven't. But I have obviously played several guitars without the with the neck shim in, and I certainly couldn't tell any before and after difference (a full length neck shim should sit somewhere between the two). I won't say there isn't any change at all, as I have to rely on my memory, and I haven't done recordings. But if there is, there's not enough difference to make a noticeable change to the way the guitar sounds when listened for. Even if there was a very small detrimental difference, for me that would be far outweighed by the increase in playability gained by fitting the shim.