This is a very good subject. :-)
I was meaning to post something like that myself, but my interest is slightly different.
My first encounter with a QSI Revolution decoder was in a Walthers N scale 2-8-8-2 loco which had a factroy installed sound decoder. It was a love at first sound! The perfect cam-less chuff synchronization with the drivers was something I have never seen - and so was the quality of all the sounds.
Ever since that time I have been hoping for a release of a smaller N scale (or H0n3) version of the QSI decoder. For a while a smaller decoder was announced on Josh's QSI site but then it disappeared. I spoke to Josh few times (in the QSI booth at the large model train show in W. SPringfield, MA) inquiring about the N scale size decoder. He said that the problem with making a smaller (N scale) decoder was the size of the QSI's custom IC (the brains of the decoder). He said that there was some talk about developing a smaller IC which would be suitable for smaller size decoders, but that has not happened as of yet. And now Josh is out of the picture anyway.
Is there any possibility that a smaller version of the QSI decoder will be produced to fit in N or H0n3 models? In those smaller models there is no need for stereo sound, so a decoder with the capabilities of the Revolution decoder would be quite satisfactory.