@Albert You are asking a big question1 if you are buying from sellers on seller financing, it is investor to investor, not owner occupied, no Dodd Frank2 if you are buying for owner occupancy on seller financing there is Dodd Frank, see a RMLO3 find a seller that wants payments over time, I compare with the owner seller financing with annuities and reverse mortgages.Albert D.undefined

Can anyone tell me what the difference is when owning small multi family units such as duplexes up to quads compared to owning 5 + units in one building?

You'll want to call around to a few banks/lenders to get a grasp of what comparable terms would be.

There are many things besides land that are unique and irreplaceable and not directly comparable to other similar things (art, literature, specialized knowledge, experience, time spent, etc.).

Some loans have a restriction on how much more you are selling the property compared to what you paid. 

Worst case scenario you learn a comparatively cheap lesson by just having a low CF house with too much dead equity in it.

Use GRM is pretty easy if you have sales prices and rents of comparable properties. 

These tend to have the best ROI when compared to other investments such as office space, warehouse, retail, etc.

The title costs will be minimal compared to the headache you will go through if you missed a lien or some other encumbrance, missed the required margin requirement on the deed, etc.  

Even their website and portal is high school quality compared to other firms.