I think you're right, that the amount of effect is pretty small. But then again, I think the aesthetics alone are sometimes worth it. It's a big effort that might not gain a huge acoustic difference "by the numbers," but since it is both aesthetically pleasant and a small improvement, that might make it worth doing for some cabinets. I guess it all depends on the style your going for.So I wouldn't want to make the acoustics a main focus for flush mount routing because I don't think it makes that big of an impact. But it doesn't hurt, and in some cases, it really looks nice.