It's like investing in stocks vs broad market index funds.

There is decent diversity in house stock; so you could invest in SFRs, duplexes, 4-plexes, and small multi-family. 

Regarding a listing agent showing a property to an unrepped buyer and potentially triggering what is called "implied agency": this is when an agent performs agency duties for a principle (buyer in this case) who they don't have a written agency agreement with, and establishes an agency relationship through their actions: https://www.prepagent.com/article/creating-agency-relationsh...Hope that helps!   

Would you rather own a stock or a mutual fund that only invests in that same stock?

of course you have to handle the inquiries… but it’s pretty easy… we’ve done it multiple times.Your 6% appreciation approximation is less than the 7% average return the stock market  does long term - and lately it has been blowing that figure away - though as they say - past performance doesn’t equal future performance. 

Our stock/bond portfolio is currently at around 30X expenses, plus we own our primary home with $200k outstanding on a low-rate mortgage.

It still made sense to purchase but unfortunately my investors got nervous at the last minute since we were in the midst of a pandemic and the stock market was doing funky things, so they pulled their cash to purchase it and all my cash was tied up elsewhere, so I had to move forward with the quad and 9 unit. 

For the reserves to replace components a decade or two out, I was hoping to get us into some exposure into an index fund (total bond, total stock, SP 500) or something but left the board before I could convince folks.

@Redgy Saint-Germain I'm currently in the process of a 203k loan and my mortgage officer said they would apply the left over balance to my mortgage balance as a principle payment, but the monthly payment would stay the same.

If you're looking for cash flow, maybe buy in the public markets (stock paying dividends, Master Limited Partnerships, Business Development Companies).