I've had both, ducted and non-ducted. I can't tell the difference in the sound. You might be able to measure it but they both sound the same to me. Our current TT does have the A/C in the bedroom area and ducted to the living room area and that does cut down on the noise a little in the LR but it's still just as loud in the bedroom as a non-ducted A/C.
However, we like the noise as it helps us sleep better. We actually run the A/C fan in the winter just to have the noise. Different strokes for different folks I guess. :)