However, its downfall (and really what makes it so easy) is that it is a single-entry system. 

We had an accounting system once that necessitated doing this - not ideal, but it keeps the assets and liabilities straight and AP is just an accrual until you pay the bill.

Summary of expensesNOICap Rate Condition of the building systems  

That system is basically: 1/ take advantage of PMLs who don't understand the market, 2/ Take that money and use it for a predatory lending scheme.

@Tammy Elias tenants are always looking to scam the system:(You'll need to start the eviction process and let the judge tell her she's wrong.

The second you are introducing metrics to change your marketing that have nothing to do with generating the leads you need, you introduce uncertainty to your systems. 

Then you can pretty easily calculate what the holding costs of that home will be and when you'll have to replace those systems.

I'm curious if anyone has a great system they'd like to share.

Did you know that you can bank with some of the newer systems for property management?

Again while they may legally be bound to an agreement, you are going to have to go through the court system to get them to abide by it, and that is not going to be easy or cheap.I see your point.