Bob did a nice job of describing the sonic differences between the KT-88 and the KT-120, rather than just talking about the mechanical and electrical differences. The differences he describes ("tubier" in particular) are often the results of differing distortion spectra between two tube types - and the curves on the two tubes seem to confirm that as the likely reason for the difference.
Also, FWIW I've had zero problems with them in the short time I've had them. That's always a good thing!!
Thanks again Bob!