What are the disadvantages of having one boiler and one furnace for a two unit house?

To be liable you must be at fault.A business entity has disadvantages, cost of maintaining the entity, legal, accounting and management.

I've done it before, there are are some advantages and disadvantages thoughif you want to close fast and hassle free, that is a spot where cash works well. one of the one's that I had bought with cash was one that needed a lot of work before it would be livable.

Are there any key advantages or disadvantages to either area that I should be aware of? 

I was loosing around 1K monthly just holding the property, so I started to run open houses on my own for one hour or so, talked to people, got very detailed feedback, added some details here and there to stress the advantages and remove attention from disadvantages, got the offer and closed the deal. 

So, I keep hearing about it being great to be classified as a "real estate Professional" for tax purposes. It seems the only benifit is to be able to deduct passive rental losses from ordinary income.. Since I have no...

Out of area investors would be at a disadvantage.

Add to that the tax disadvantages and other concerns and this starts to become a very risky strategy of dubious benefit to begin with. 

Each asset class has a profile and advantages and disadvantages.

Advantages and disadvantages to the "Full Service" approach.