My questions relates to the accuracy of the appraisal.

Nick,You’ve got some solid advice here on how to get to the point that your analysis has a high degree of accuracy.  

As far as accuracy I would turn to any local investors in your area and see exactly what they have been seeing in their rentals.

Cannot be sure of accuracy until sold...so it is an educated guess.

It varies by market, but around here, Zillow's own claim for the accuracy of their "Zestimates" is awful. 

They seem to be asking $1,000+ to BUY IN Has ANYONE tried using it to see if it has produced results for them in the following areas:1) Ease of use & interface- reasonable learning curve2) Accuracy of the Data (Property owners Phone #s, Email addresses, Social Media contact info, etc.)3) Any hidden ongoing costs?

The way to double check the tax accuracy is start with the listed accessed value of the property, you would expect that to be correct on the listing.Or search online for the county Assessment office, and find the listing on the Assessment website.Next search for millage rates or property tax rates in the county.In my area of PA there is:MUNICIPALSCHOOLCOUNTYRemember they come due at different times and when you pay affects the amount due.Plus factor in annual increases.This would also be helpful to know which school districts or municipalities have higher or lower rates.  

No one can predict what is going to happen to the market with 100% accuracy. 

Fannie's predicting 10 and 20 years into the future, which will obviously cause accuracy concerns, but the numbers are there.Yes, I agree there will be a lot of elder mom-n-pop landlords ready to retire and get rid of their multi-family unit, but there will also be a lot of buyers waiting to make overpriced offers as more and more people get into the MF game. 

Not sure on the accuracy though, since land lines are going the way of the dinosaur...