Hi Max. Thanks for the comment. First, certainly paying off your mortgage is much better than what most people do (which is not save enough or pay down their mortgage).
The math is likely to favor investing over paying down a low-interest mortgage in most scenarios. But as you point out it’s about more than the math. If paying off the mortgage before retirement makes you feel better, by all means.
The point I make in the article is that all things being equal investing is likely the optimal solution. But each person has to evaluate their personal circumstances before the make such a decision. Sounds like you have done just that.