Some will say pay it all off, but then the argument is that you'll deplete all cash that would essentially be allocated for investment purposes.

She basically said that they do not allocate any money for vacancy because they tell you how to get great tenants (but even the best lose their jobs I have found). 

If you reinvested the cash returns into an additional deal every 3-5 years, while also allocating even more additional personal capital each year, the compounded cash flow 10-20 years down the road, once you now have 5,10,15 different investments, looks very solid.

@Sunny Burns, yes, your math is correct.However, there may be other reasonable ways of allocating your property tax deductions among the units that may result in you being able to shift more property taxes to Schedule E, which I imagine you'd want to do given @Chiwei C. 

How does this work for partially shared areas (i.e. 2 rooms are allocated to 1 bathroom).

The home is very solid so I allocated $600 per year for maint. 

They put everyone through a wizard which supposedly allocates you basically risk.

In my opinion there isn’t a fair way to allocate heat usage given your current setup.  

Use that for investment for a period of time (there is again no statutory limit conservative wisdom recommends a year or two), and then change your mind and convert it to your primary residence  Changing the use does no trigger a recognition of gain and once you have lived in it for 2 out of the previous 5 year period and have owned the property for at least 5 years you can either continue to live in the property or sell it and take at least some of the gain tax free (it will be %allocated between qualifying, primary residence, and non-qualifying, investment use)Hard and fixed guidelines are few but the practice is very prevalent and with good guidance and planning you can accomplish this or a variation very easily.

Arranging title, such as Tenants In Common or Joint Tenants, to relate to the equity allocation of each owner on title.