Typical guru always comes back with claims of a room full of attorneys blessing their system or product and denying any unethical or illegal aspects.  

The difficulty really depends upon how the heating system was installed from the get go.  

I wish that I could trust and believe in there system but in the end I have to go with my gut!

Some are more expensive than others (HOA) fees, some have central water and sewers while others have well and septic systems; most all have recreational facilities; you will find a wide range of prices, dues and taxes.  

I use a system for my flooring and types of things that I do to my rentals.  

The East Bay is where most of the gentrification in the Bay is happening, with the rapid-transit system, BART, being the main engine of growth for people who want a quick commute into their jobs in San Francisco.

Having to do an engineered system is usually a deal buster as they are very expensive

These homes will require a new kitchen, HVAC system, and finishes.I'm assuming on these properties I will be required to get a construction loan.

Ethics are not legislated in many cases but imposed under our legal system under concepts of common and uniform law. 

It's a little dated but still really good book on creating systems.