I also know that any attempt at accuracy would require itemizing my likely future expenses, their cost, and estimating when those costs may need to be addressed.

If you can find 60 and three of them are within 1/4 mile of the home you are studying, then you'll get better accuracy.

I was questioning the accuracy of the property manager because the typical house they manage is anywhere from 5-8 bedrooms and does 90% of its business during the summer. 

It's always important to carefully evaluate any potential investment and consider a variety of factors before making a decision.One thing to consider is the accuracy of the data you are using to analyze the property.

However, it is how you are supposed to report it for accuracy, before we even consider the potential benefit to you.

And the founder of Property Radar has something like 120 rules to try to maintain best chance of accuracy along with tools for professionals so am leaning more towards his way.

Account Closed I cannot verify its accuracy, but please see the link below that I just pulled up for transfer tax issues at least.http://www.anytimeestimate.com/PA_REAL_ESTATE_TAX/pa-transfer-tax.htm

Ultimate Skip Trace says they can do 94% accuracy but won't let me do a small test. 

Again, couldn’t agree more that the rentalyzer isn’t carved in Stone accuracy, but so far we’ve been able to beat the rentalyzer metrics by at least a 20% standard deviation on all of our listings, so it’s a great benchmark for us.

A 2nd mortgage foreclosing is a big red flag for me and strange that someone will be paying a 1st position and allowing the property to be foreclosed on.I would dig deeper to make sure there are no other liens attached to the property that when adding all those liens, the 1st position and your inverstment amount does not surpass the property value.If they don't a quick exit is to sell it where there's still money left to get a return.If they do add to more then hurry and rent it get some of your investment back and with luck get some ROI.I stay away from 2nd positions unless you know with perfect accuracy the financial details of what can be attached to that property, it just doesn't make sense that someone with only 2 mortgages will default on the smaller amount and not the first SPECIALLY if theres equity.Good luck!