Yeah I doubt a bond would pay that well.. but he does have a point about risk exposure. Your mortgage could be thought of as an investment in the local real estate market.. diversifying that risk by buying shares in a REIT could be a good strategy... especially if you're in a low-growth area (ie outside of the big cities, midwest, etc).

Hey, here's a shockingly simple idea: don't buy a home if you don't want equity, rent instead.

There are systematic advantages to having a mortgage vs renting.

Maybe not, but you can easily move into lower grade and higher yield debt depending on the interest rate of your mortgage.