I'm picking up on this thread as currently trying to narrow down my property manager search in Houston.

Don’t sellers pick their own title company?

Anything less is recreational and they'll be learning on your dime and you won't even know it. 

Also, when picking a lender, make sure you pick one that is very familiar with BRRRR strategies, has access to hundreds of lenders to shop the best Hard Money and Refinance partners for you, and that can give you advise on the front end.  

And for the implementation and testing of these, have people tried to change over in the course of a month or picked a reliable tenant as a tester or something in between?

An agent would be invaluable to you to pick through each of these neighborhoods.

I understand equity and cash-flow are related, but what I mean is that I don't need the cash flow right now as much as I'd like to build a strong portfolio that can cash flow even more later on.I've owned a single-family rental for 4 years, but on mulitple fronts I felt like I've done a poor job self-managing it, so this Fall I picked up the Turners' book on managing rentals and that's what led me here to Bigger Pockets online.

You’ll pick up so much just by listening to people who’ve been through the highs and lows of the market.

If i'm ever in the NE area I will sure to reach out to further pick your brain.

.)- If use the property more than 15 days or 10% of the time it becomes a residenceI suspect this is part of why the STR trend has picked up so greatly amongst professionals working in tech.