As @Karen Margrave mentioned, there's a ton of details related to the zoning and topography - principally whether the lot is level and graded yet or not, as well as whether there's water meter(s) and such already in place - that have big impacts on your costs and hold time.  

IMO, it appears that the water from the down spout may not be diverted away from the house, flowing to the left to the corner and allowing the foundation to settle toward the left.I'd check the soil! 

There is not the unknown of the water not turning on, the pipes bursting, the outside not being cared etc.

Taxes- $1,312Sewer and Water- (paid by tenant) $90/moTrash- $0Heat/Utilities- (paid by tenant) $130/moHOA- $0Cap Ex and Ops (my personal minimum is $150/roof/month)- I had planned on 10%. 

Water sits on the window sill and warps the wood. 

Water dispensers mean floods.  

On Sunday morning, we got a call from the neighbors saying that there was a lot of water coming out of our garage!

Build the system, step away, be a service missionary with my wife and kids (e.g. bring clean water systems to third-world villages, disaster relief, etc.)"

Purchase price: 270kCurrently rented for: 3500/monthExpenses: 600/month (taxes, insurance, utilities < water for one unit)Prop Mgt: 300/month Maintainance: 120/monthCapEx/Rainy day:  230/monthVacancy: 175/ month (5%)Debt service:  1090/ month (@5% interest)Total:  2500 (approx)Cash Flow:  1000/month (200 per door)Downpayment: 70k (25%)Cash on Cash: 17%What are the downsides of such a package against a multifamily unit?

Next you might consider looking into any drainage issues with the lots and excavation issues and or limitations.