@JPB,
The only problem I see with that cap is that home prices differ from location to location - even ZIP code to ZIP code.
A good example is in our town of Sunnyvale where our ZIP code has homes for over $1 million, but the other ZIP codes have homes for $200k, and we're just a few miles apart.
I'm sure there are other issues that I can't think of now, but it's somewhat similar to what happened in the case of PROP 13 in California where our property tax is perhaps one of the lowest in our area, because we've lived here the longest.
Our neighbors living in the same style home can be paying thousands in property tax every month, while we pay that for the whole year.
There needs to be some sort of fairness to these long-term tax codes.