Clear opportunity for improvement How did you find this deal and how did you negotiate it?

How do other regular condos perform versus them? 

I'd say the logical paradigm in the question is a bit off.CRE includes everything from airports to golf courses to hospitals to campgrounds.So saying "residential versus commercial" is like saying "bacon versus plant life."

What's his home improvement contractors license?

They may sell in a few years when interest rates drop or keep it longer term as cash flow on the property improves!

They may argue they couldn't pay you because they just made a $10,000 improvement to the house. 

Plenty exist for private lenders (which is what seller financing is) and can track payments and am tables and also do automatic electronic withdrawal (ACH debit) which helps improve the likelihood of getting paid promptly each month.

However based on these experiences still seem too risky versus just going after some of the options with RealCrowd that seem attractive and proven. 

Proceeds to segregated account to be disbursed ONLY on rental property improvements and expenses to preserve the deductibility of interest on your Schedule E.

There is some future Infrastructure improvements taking place, which can/cannot impact the property ROI.