Payoff Mortgage or Keep Money Invested?

Borrow Smart Community: What is the best calculator to use for below?

I’ve got a fellow mortgage advisor at my company having a ‘marital dispute’. ;-) To liquidate existing savings to pay off mortgage (husband) or keep money invested and continue paying down mortgage gradually (mortgage advisor wife).

• Current balance on their mortgage is $200k; 3.5% interest, $2,100 P&I

• 9 years left on mortgage.

• Investments of $200k+ making 10% on average.

• They DO deduct mortgage interest.

• They would expect to pay 15% capital gains on money they liquidate.

• Hubby argues they’d free up $2,100 per month for improved cash flow. Wife says that’s insane due to the cost of the mortgage and return on the investments.

We all know the logical answer here, but primary question is, where’s the best calculator I could share with her to SHOW her husband? (She did it on the back of a napkin so far ;-)

I’ve already walked her through some key Borrow Smart talking points and concepts. …but not sure the Pre-Payment Analyzer is the best one for this all-or-nothing scenario?