Provided I can establish a solid investment plan tailored to their financial needs/comforts such as debt ratios and income, they would be more than happy to offer me some financial control.Additionally, If I wanted to, for the sake of building my own personal wealth, I admittedly have the luxury of taking a loan from my parents.

Personally, I'd go with the As-Is scenario.

To wait until, the actions of others, made things look "cheap". 

We would want to use it for personal use probably one per year. 

While personal loss is difficult and understandable, running a business that directly impacts property owners requires a contingency plan.

This is so I know if I should keep the person I currently have.

I personally use 40% but I'm also in a higher rent area.

I personally would not invest in detroit as historically its not a appreciating market and for cash flow and I invest primarily for appreciation - I go off the location location location mantra. 

One-person rental units are in the highest demand, and co-living directly appeals to this market.

Tell me - someone selling their home to your son, Subject-To - is this a person who has made good life choices?