[LUmBULtERA]

My mortgage is at 2.625%. If I have the cash, even 1 month T-Bills are paying a higher rate than that (about 3.6%). Assume I have the cash to pay it off -- I'm strictly worse off if I pay off the mortgage vs. even investing in 1-month t-Bills.

[toomuchtodo]

Close. Depends on your marginal tax rate and returns post tax compared to the debt rate of interest. At higher tax rates, it gets closer to being a wash with the spread still low. If risk free rates continue to rise, the investment vs pay down benefit becomes more clear.