Challenges mostly revolved around having to lease out a different unit unexpectedly during a slow rental market in MN winter, and dealing with an onslaught of maintenance issues at my other properties.

With skinny cash flow, a few unexpected repair bills or bad tenants could put you in a rough spot for cash flow.

My point was that if you intend to create massive wealth and do so with out the difficult efforts of finding 100+ individual doors, and also do so from a passive or semi passive standpoint, then multifamily would be the best choice in my opinion (or something similar like other commercial class buildings).Thanks for your comments David, I think we are the on the same page and your last comment allowed me to respond with more details.Yep agreed ... guess where I vary from most is that I have no desire for "massive wealth" as you have it defined and definitely have no desire for the risks and persistent PIA it would take to get and stay there, though I'm still fairly young and ironically I may ultimately get their by accident by re-investing my "reasonable margin" on excess passive income over time ... no matter your income ($20k/mo or $100k+/mo, passive or otherwise), if your margin over expenses is continuously zero or negative you are not wealthy nor will you ever be ... if it takes a majority of your time (your most valuable asset) to create that income and the income will stop the second your effort stops, then you equally are also not wealthy IMO.

Think of it as an unexpected expense in the property you bought, the deal most likely is still solid. 

Has anyone gotten a HELOC on their investment properties as a way to protect them from a rainy day in their personal lives (job loss, unexpected medical costs)??

i told Ben we will touch base in a couple days and take it to the next step....Ben died two nights ago, unexpectedly.  

You need three things to protect you from market risk in a downturn:Equity, which gives you more options to sell if you need or choose to or refinance.Cash reserves, to pay expenses, unexpected CapEx, vacancies which could increase in a recession as your tenants lose their job, etc.Cash flow.

If possible, get the hard money loan for a longer period of time.  6 months is tight and you want to look for the unexpected.  

Carpets will get dirty a lot faster even without accidents - the dogs simply track in more dirt.

A car accident, cancer or heart attack make a life time of hoarding cash in a property a total waste.The kicker is no one wants to believe it will happen to them.Life is often too short to work for nothing except retirement.