If you include some older comps you will get a more conservative number and this is more likely to be accurate (but still should be a lot higher than the county tax assessment). 

Remember, buyers will assess the design and quality of the home before making an offer.

I've purchased a few dozen with SF and never used an agent.

That's funny, because the Bigger Pockets Best and Worst Markets for Residential Real Estate Investors, 2016 recently listed Providence in the "The 10 Worst Markets for Real Estate Investors".Between the two, I think I agree with the Bigger Pockets assessment over the Realtor(R) research, at least for the evaluation of Providence/RI.

I run PPC for dozens of investors.

That's the only way you're going to get eyes on the property and get an accurate assessment.

You are subject to special assessments and increase in dues with no real say in the matter.

Perhaps there is more information that we need to assess?

I have worked with dozens of "investors" over the years.

So you do want to weigh that against a potential tax re-assessment etc.