I agree renters take less care of a home, property, and neighborhood than an owner does.

You will net much more cash than an LTR.  

Exiting an SFR deal is much easier than an multi-family, more available buyers and a bigger market for renters. 

Well, if you say appreciation for a specific neighborhood is 2%, a renovated 500K house will appreciate more than an unrenovated 300K house, even at the same 2%.

After exhausted with 10 conventional loan, I purchased more properties using hard money lender.After more equity is built, then I used portfolio loans to replace all previous hard money loans.

Seems that single family outside of the city would generate higher rents and less taxes.Everyone selling a 2-4 unit property is looking for an owner occupant - they are always willing and able to spend more than an investor. 

If I were 25 years old, defaulting could be a solution, albeit a last resort after exhausting all other options, but where I am now, defaulting like that would ruin the rest of my life, so I would avoid it at all cost.

As @Nathan Yaun pointed out, a HELOC is a Home Equity Line Of Credit.Why a line of credit rather than an amortized loan?

You do realize that portfolio lenders want a higher down payment and people go to portfolio lenders once they have exhausted their Fannie/Freddie loans.

There are other options available than an FHA loan, its best you started saving if you plan to buy property.