Thanks for all the great information!
I happen to have 2 YMF-724-based PC sound cards - and I have Power Tracks and Band-in-a-box. But as I mentioned in the first post, my S.O. needs a blonde compliant keyboard.
She is particular about subtle things like keyboard feel, and color (Green is her favorite). She is reluctant to delve into the software I already have. Sigh...
I have recently become intrigued by the Casio MZ-2000. It has been offered by zZounds at less than $1100. It has many features that previous CASIOs didn't - e.g., Line in and Mic in, that can access internal DSP.
But I suspect they haven't upgraded their keyboards, nor their sound samples. There is no mention of the size of ROM in the unit.