Fort Collins did it since the 1960s and only recently created a law against it because of rent rates.

Those are spray and pray techniques that don't fit with sellers right now because sellers/owners are sitting on a very low rate and don't want to move to go up 4-5 points on their rate.Listings aren't a start now thing as well.

This is a self directed RRSP or TFSA account that allows you to lend your money out to people with the backing of their mortgage for a high interest rate. 1st, 2nd, 3rd mortgages, down payments, refinances, flipping or renovation money.

Do you think this strategy gains strength if lets say... in five years interest rates are at 5.5 vs 7.5 now?  

You would end up saving the higher interest rate on the HELOC as well as closing costs.

Quote from @John Warren: @Mordechai Chaimovitz cap rates and NOI are commercial real estate terms, and 1-4 units are not really valued in the same way.

@Loren Souers I'd have to run the specific scenarios with the rates and fees, but if you're OK with paying the higher closing costs, the Mortgage 1 deal looks good, particularly if you focus on CoC returns.

There are quite a number of things that can make utilizing an FHA loan more difficult such as more barriers during appraisal, appearance of low qualification/little cash, typically longer closing period, likely higher interest rate, and PMI cannot be dropped without a refinance if 3.5% down.That said, just chain 5% down conventional loans, and make sure your duplexes pay for themselves.  

Rental rate?

Keep in mind a HELOC rate will be much higher because of the CLTV and risk.