I am constantly amazed that the economy of scale with the MFU is not self apparent and given equal opportunity(meaning loan qualification for either/or), an investor would opt for SFRs instead.
I am an absentee owner of a 6-plex 120miles away. Try doing that with six different locations at different points on the compass from home. Yea I burn 2hrs one-way but IRS mileage deduction PAYS me to drive to-and-fro :)
The MFU has another economic advantage other than just building maintenance: I've forced grown the property value! In '97 I bought at 305k; current escrow is at 775k. That's 254% growth in property value (some might read this appreciation). Take 254% / 18 yrs is 14% growth per year - - in San Bernardino County. Many will cite 2-3% appreciation per year in good times. Anyone holding in 2008 knows it's not always rosie.
Another metric (or measure) is NOI/door. In '97 it was $280/door; today it's $577/door.
What was the magic? Simply increasing rents. A $10 increase times six units nets +60 to the NOI. @Brian Turnbough Any improvement to all units adds value times six and the SFR doesn't have any such multiplier; just dollar for dollar. We all know the cash-on-cash and cap rate math depend on NOI so it's easily seen that the property value grows over time by how you manage your GSI.
There is one major advantage to holding SFRs; you can partially liquidate and still retain an income stream. I attempted to bifurcate (divide) the two triplex's to make that opportunity as an exit option, but zoning requirement and city planners would not consider a zoning variance, so that thought went up in smoke.
IMO, it's the entry price to MFUs that kill the opportunity for the beginning investor. The higher LTV requirement becomes insurmountable to most, but especially those seek creative or no money down opportunities.
The two triplex's is a rare find, but 4plexes will perform similarly for the small investor and I highly recommend rolling a couple of SFRs into a 4plex at your earliest opportunity.