I acquired a property couple years ago and did a BRRRR on it.

Purchase price: $245,000 Cash invested: $80,000 I served as the buyer's agent acquiring this property.

For example, should we focus on acquiring one high-quality property in a strong market, or would it make more sense to spread the investment across multiple lower-cost units in emerging areas?

If you take out debt to acquire, you will be negatively leveraged.  

If you can make a better return by using that cash on a different deal & you're in the "growth phase" most investors wouldn't buy it down because they would prioritize acquiring more properties over maximizing cash flow now.

They acquired the neighboring four-unit in the 1990s for $150,000.00.

Brian Burke has acquired over half a billion dollars’ worth of real estate over a 30-year career, including thousands of multifamily units and more than 700 single-family homes, with the assistance of proprietary software that he wrote himself.

Question to you then - how and when did you acquire the properties you have now?

Specifically, the the loan guarantors need to have controlling ownership in at least (i) 3 multifamily properties [with the first acquired at least 2 years ago], or (ii) 1 multifamily property that has been owned for at least the last 5 years. 

I know a lot of investors do this, they acquire properties and then sell them under their terms, acting as a bank financing a purchase.