But I would say I'm generally an advocate for settlement or cash-for-keys approach.

At the end of the day you have a promise to pay from a stranger, and if they don't pay the lease is your legal framework to force payment from a court.

It will impact her credit and if she ever receives money from an insurance settlement or judgement (or if she's willed a house and sells it) you'll get paid. 

It will impact her credit and in the event she comes into money (such as an insurance settlement or she inherits a house from a family member and sells it) the money will go toward the money owed to you. 

That "broke *** loser" might be waiting on a lawsuit settlement or an inheritance, OR might be testing you (banks even hire testers).Of course smart people buy condos or homes the second they can afford one.  

I've had people offer me this after they've gotten a big settlement from..... nuisance lawsuit against a former landlord! 

Find a Settlement company or lawyer (depending if you have state that requires lawyers) that will provide a simple contract with your terms and then execute the transaction.

I just spoke with my tenant about her moving out and me prorating the rent as she is requesting. she agreed that would work for her and no further legal action would be held against me. i got her to agree to signing something saying she would not sue me for the rent money or any medical issues that could have possibly arose from her staying in my house. she agreed to sign a settlement document.

Create a strict framework for your deal and only buy if it fits that framework.  

That's how I mainly use it - to get people to quit blowing me off and give me a fair settlement.