The only downside, from my perspective, is that if you don't buy right and have sufficient cash reserves, you might lock up that money for a looonnnggg time, which is not good- you aren't liquid and interest rates are variable and out of your control.

However, as a broker, if you do many deals, you'll have significant income that can afford full cash purchase or income sufficient to justify a flip with bad debt.Normal W-2 jobs alleviate issues with income requirements.

However, if you have appreciation or principal pay down, or both, the collateral may still be sufficient.  

The title company won't accept this either.The current owner has been trying to get in touch with the prior owner's family to issue a mortgage satisfaction statement, as the prior owner / lien holder passed away some years ago.My questions are, if we do get a statement from the family, is that sufficient proof of mortgage satisfaction as far as the title company is concerned, and is it enough legal protection in case the family changes their mind down the road at some point?

This would be rents from the other 3 units.If this is a 4 unit property it must also meet the self sufficiency test of FHA which is if you were to rent out all 4 units on a gross rents basis that there would be enough to income to cover the PITIA (prin/int/tax/ins/assessments).FHA's rule I found was a bit vague as ive talked to different FHA underwriters and my head Gov't policy underwriter but you can have a maximum of 7 financed properties including the proposed property youre trying to purchase.

So that means minimizing your out-of-pocket.I'm generally in favor of maximizing leverage if you can get long term fixed rate financing, AND your property income is still sufficient to absorb the ups and downs that can occur when owning rental property.

There are issues such as elderly/handicap access and sufficient parking but on the most part, can't office buildings easily be converted?  

You have no debt service and only pay a token rent (maybe $100/month/door? 

Also, a credit score is not sufficient to make a decision on.

They don't generally make sufficient income to afford professional management.