It's a decision that you have to make based on your own personal risk tolerance.

You can acquire during different phases if you know how to work them.If you think of a timeline, you can imagine that becoming aware of a property owned by a deceased person can be determine prior to, during or after probate distribution.Acquiring pre-private can take some real skil...and a high tolerance for risk. 

So KISS:- Use an LLC in the state you have a rental- don't do "holding entities" unless there is a very specific reason you want to do with a "holding entity"- Create a new LLC for new batch of rental only in relation to your personal risk tolerance - use an S-corp for active business and you will pay a salary (rentals are considered passive not active)Now in the future when you become a multiconglomerate business, then hire a team of lawyers and accountants to restructure everything for you.

It has a lot to do with personal tolerance.

@Hiro KitagawaHiro: One thing you might consider is Cinci's tolerance of Airbnb.

Various ways to structure this with your risk tolerance.

Are note buyers just inherently more risk tolerant?

The choice is very personal and depends on several factors including your risk tolerance, what other assets each of you may have, the likelihood of tenants or visitors suing you, the general condition of the property, whether you have good property management, your other estate planning that you have in place, etc.  

I own one SFH which is slightly cash-flow positive, and based on savings and income from other sources, I can likely tolerate a few months of vacancy.

No one can predict the future and you need to decide your goals and risk tolerance.