Depends on what rents you are expecting versus the market.

Versus a $100k house in Columbus, OH that has weaker cash flow, but might appreciate or at least keep it's value and I can get a mortgage for. 

I would love to talk to you about partnering on some deals in this area if you are willing to take a look at investing in this location versus the bigger markets (which I find to be over saturated and heavily effected by downturns). 

I would wager he doesn't have $5,000.  

You didn't mention have much money you make per year with your job or business.The plan might be different if you make 50k a barely squeak by versus 100k and some additional income.Regeneration of capital on a monthly basis is a key factor.

Current occupants are paying $650/month per unit, Rentometer says median is $710 so I'm estimating this deal using median rent versus current rent after a few thousand invested in improvements. 

Hope this makes sense, but was listening to episode 269 with Amanda Han and Brandon Hall, and it got me wondering.Is there any real net- benefit from owning a relatives home and having them pay you rent versus them simply owning the home themselves?

Regarding duplex versus 4br, I would normally say the duplex because it can be busy to rent out individual bedrooms.

A duplex you can cash out at an LTV of 75% as a primary versus 70% as an investment property. 

In my area the roi is a good 4-6% better on houses versus multi family.