I’d love to hear your experiences—positive or negative—and learn what worked well (or didn’t). 

The reality is a property worth $375 that can rent for $2100 max is always going to be a poor rental.Using 50% expenses (50% rule)2100 (rent) - $1050 (expenses other than mortgage) - $2047 = negative $997You can see even at a 40% expense ratio, this would be negative)   Even at 30% expense ratio this is negative.  

(Due on Sale clause in the loan agreement)I only buy Subject to, but there is an art form to it.

You could easily pay 3-5% in a prepayment penalty that would negate years of rate savings if it does not make sense.

Interest rates are 6-7.5% so at 3.5% down and if you could have everyone paying rent, you're probably negative cash flow.

I am not an agent, and I only know about you what you posted, but... is becoming an RE agent an easy way to make quick cash from home? 

That takes your loan down another $200K and is probably the difference maker in being negative vs positive.

Curious as to whether anyone uses them and has anything negative to say.

We are in the DC area and I have never heard negative comments about them. 

If you buy a property all cash, you’ll maximize cash flow—but most investors use financing, which means interest rates and down payment size will directly affect returns.Cash flow can quickly turn negative with major repairs or long vacancies.