I am not a fan of this model, since it reduces cash flow, but is this a viable option for raising money?

They are similar in how you financially model (NOI, cap rates, etc.) but the component parts and various risks are quite different.  

The excess capital generated by the real estate business is used to passively invest in real estate opportunities.Sure, this model is a lot of work... but to exactly John C's point above, i'm not in a rush to leave behind a career that I enjoy, find fulfilling and pays for more than 100% of our lifestyle ... only to 'retire' before the active real estate business has started generating at least as much as the primary day job does.

Assuming the services are provided adequately and equally, which model provides the best value to me?

They also looked into replacing washing machines with energy efficient models to reduce usage. 

Create a Model: Facebook started off at a single school.

How could the pricing model differ from a co-op ?

Do you feel that is a model that serves both the investor client and tenant?

My biggest concern with seller financing models is the due on sale claus in the already existing conventional mortage for the property. 

That is the appraisal model for determine property value in residential real estate.