As far as tax deduction is concerned, it has to do with
a) your marginal tax rate for the mortgage portion. It may not be your highest tax braket.
b) whether AMT comes into play for you.

And I assume that you’ve already itemized before a mortage due to state tax.

The max tax saving is total deductible amount (interest + property tax) x your marginal tax rate. Your realized saving might be lower due to the above factors.