The investment portion of 3 units equals their reinvestment target of $600K. 

You are excluding possibly the majority of available tenants to focus on the most difficult to manage and the ones who are most likely to leave your property heavily worn and damaged, all other things being equal.

.), index funds are likely to provide an equal or better return with a MUCH lower hassle factor and more liquidity.

All things being equal.  

Otherwise, you may be limited to doing deals that are less than or equal to the equity in your home, and miss out on some bigger opportunities.That said, fix-and-flip loans will have higher fees and interest rates than most HELOC's.

However, if that effort fails, the local agent is equally liable – criminally and civilly – for any fees, fines, etc. associated with the property." 

Consider this, as an “experiment”, 24 months ago I invested $300,000 in equal amounts ($30,000 in each) in 10 speculative small REITs.  

So is it equally illegal when the large landlords drop rental prices in a building as vacancy increases and the market softens?

If the loan was fully funded at closing and since then the loan is in an interest-only payment period, these numbers would equal. 

@Kyle Carter "Section 8 sometimes can bring in slightly higher rents, with that the NOI goes up (all things equal)."