We saw huge appreciation in the 2018-2022 inflation run up, but that has significantly slowed these days in my opinion.From a rental perspective your monthly income per unit after all expenses with a typical 20% down payment is likely $100-300 when you find a property that will cash flow.

However , properties taxes are due like roughly 12k for the two lots. 

You also don't have to pay state tax on income. 

After all expenses, including PITI, we net on average $700/month.

After sitting vacant for a while I'm entertaining the option of converting to residential units.

People that get destroyed are ones that are enticed by the low interest rate and assume they can refi after the second year. 

Weigh the long-term benefits of the low mortgage rate you have versus selling and getting $500k from a sale exempt from capital gains tax.

Most people would walk away after something like that, but he used the experience to build his expertise and now owns 50+ units.

They put one of their employees into one of my houses, and after I switched to a new property manager, that tenant stopped paying rent (amazing!)  

The 4-plex would produce around $1000/mo cash flow after financing, and that financing would recover your total build cost leaving you with no money in the deal at the end and an "infinite return" for CoC.