Great question @Lorraine Hadden,You should always compare both side by side to see the advantages /disadvantages to each.

Credit Union, Brokers, Banks (all have different advantage & disadvantages). 

But there are also some disadvantages.

Nearly half of our reservations come with pets and to not allow them would put you at a severe disadvantage in a competitive market.

When January comes, you will have two disadvantages:- you will have missed on the end-of-year planning opportunities- some of the most highly sought after professionals will be full and not taking clients anymoreAnd the longer you wait, the fewer choices you will have. 

As a resident (who travels a lot) I would say the Midwest does not have the attractions like palm trees & beaches (the great lakes are cold) or amazing mountain ranges, which often come with some disadvantages like high cost of living or hut/humid weather, stroms etc. 

Which means not only is it not working to your advantage, but it's actively working to your disadvantage...As seen here:@Gary Floring Lets say you took out a $100k mortgage @5%, with a monthly payment of 536.82.

I maintain even break even on valuation (which is rare in SF Zoned areas), the ADU has big disadvantages versus new property acquisition including financing, level of effort, rent control, prop tax being based on cost rather than value added, length of time including length of time from first expenditures to first income, reduction of something from existing unit (in your case existing home lost its garage).Did you see starting next year Mf can add an ADU per unit up to 8 units without any affordable housing concessions?

Realistically, there should be no benefit, and there are probably some disadvantages, of doing what you propose.

One of the disadvantages is if I add an ADU to my single family rental, it's considered a 2 unit and under rent control so I decided not to do that considering all the construction costs.