@ Dave DeMarinis excellent analysis. I agree with mostly everything you put forward but I would like to respectfully add some content for consideration.
(1) Single family houses are not necessarily readily available to rent. The rental market is so competitive that most people do not list their homes for rent, they all have waiting lists. Rental homes are difficult to find, especially for renters seeking to pay $1000 or below.
(2) Most small Multi-Family buyers I have run across are more interested in cash-flow than in appreciation. The duplexes and quads often offer great cashflow with less risk because the rent is spread across several renters. These units also seem to be appreciating at the same rate or a little faster of the market.
(3) Turnover is typically higher. Most renting between 12 and 24 months but they are exceptionally easy to find tenants for. Most 2 bedrooms/1 bathroom in C+/B- areas do not stay unoccupied for more than a week.