With gas (or propane) you need a chimney for gravity vent units, that means you now have to properly maintain the chimney and possibly install a liner, repair masonry, etc.

Wow that house even has broken gravity!

One can only hope so, but the markets in many parts of Canada have been defying gravity - and mathematics - for so long that people now believe it to be normal.It certainly appears to have peaked for us ... we have not bought anything in over a year now and are 0.5 for 8 on 12+ unit properties in our area {the 0.5 reflects an interim position we have taken in a property with another investor}.

The joists sit on the sill and gravity does the rest but in order to jack the house you need to brace with temp beams and jack as far out on the joists as possible.

Supply lines are easy with pex but drain lines and gravity create some significant challenges. 

No, I have no intent to fight them, it's like fighting gravity.

Those will have a common boiler or gravity furnaces.

Podio is a great tool for your data management and the integration possibilities to other 3rd party apps is nearly endless; Globiflow, Zapier, Gravity forms, Webmerge, Signnow etc

It's like gravity.

The ONLY reason there is gravity, is because my head is SO big, it generates its own gravity field.