@Collin Luckett what your touching on for changing of buyer during pending is not a viable direction. 

It would be great if your rental could also work financially as a long-term rental if the STR market changes.  

Quote from @Marc Shin: I saw a video by Miles Golden and he said you change transfer your primary mortgage to a HELOC, and then you can pay all your bills out of the HELOC and pay off your mortgage in 3-12 years. 

While some folks may not change the way they underwrite from one type of property to another, what specific property are you interested in, SF, 2-4 MF, or 5+ MF? 

It won't change the payment unless you refinance.

As long as the buyer prioritize lower monthly payments and is confident that they can manage the long-term cost of a 40-yr loan - If the buyer plans to stay in the property for a long time.Also, be sure to weigh these two drawbacks to a 40-year loan (paying significantly more interest over the life of the loan and building equity slower as compared to a shorter loan term).

We knew starting out we wanted to create systems and RentRedi met our needs. 

Ultimately it's less of a science than an art, but people rarely truly change so what they did is probably what they'll do.

Sellers are notorious for not communicating any changes in their unit counts to avoid paying taxes.  

Makes life way easier as tenants can't go complaining to you about it as its their own responsibility.