My approach:
I created a separate taxable investment account that I labelled my "mortgage savings account" and it really helps me see progress. The plan is when I quit paid employment, or if mortgage interest spikes, I would just divert funds then. Until then, I don't actually NEED the money on the low interest (2.1%) mortgage I have.
My differences are:
1. Mortgage is a large amount (HCOL)- about half the value of my retirement investment, with many more years to pay off.
2. I chose a variable ARM for the lowest possible rate, but was having stress attacks worrying about interest increases until I created the dedicated separate account as a buffer.
3. I don't get the mortgage tax deduction for mortgage that many others on the forum recoup. This was all about not locking up the funds too firmly, while getting the best NET return, with the least stress and most freedom for me.