Well, apparently the problem goes deeper than just creating a User Program list with two entries. It seems that the parameter "Hold" functionality for User Programs doesn't always work as designed.

I'm trying to select a new user program that maintains EVERYTHING currently in memory: Tones, Style, Tempo, Keyboard mode, etc. Everything EXCEPT the Bass Inversion setting. I spent almost two hours last night trying every reasonable combination of check boxes, saving and re-saving the User Programs, etc. When I activate "Hold," the bass inversion setting does not inherit from the user program as expected. It seems that the programmers bundled this setting with the Style. If I allow the UPG to change the style, the style variation and bass inversion setting also change. But when I lock out the style change, it ignores the bass inversion setting coming from the new UPG. I consider this a software bug, because there is a separately selectable parameter for Bass Inversion. Clearly the intent was to allow the user to change only this parameter. However, it doesn't work!!

If someone has firsthand experience with parameter hold (I'm attempting this on an E-50; it's called "lock" on the newer BKs) and knows how to make this work, i.e., what step I'm missing, I would really appreciate some guidance. Thanks!!