I have brought this up in multiple Prop 13 discussions, including I think the one you are referring to where you pitched your proposal. My opinion is that the proper fix for Prop 13 is to modify it to match Florida's much saner[1] practice of only providing the appreciation cap to owner-occupied primary residences. That speculators, investors, and landlords get to benefit from taxable value caps is bullshit, IMNSHO.

[1] Who would have expected Florida to be the same one on anything?