But rents are extremely high and vacancies are rare.

My guess is that its price/rent ratio can't readily be improved, without risking higher vacancy rate?

The rental market, aka vacancy rates should remain good in Fort Collins, but from an investment standpoint, ROI and cash-on-cash is not looking real good.

I always have several rent applicants every time I have a vacancy. 

But my break-even was 6 units and at the time the vacancy rate was about 20% and I bought both multi's at a 14 cap.  

The advantages are numerous but the big ones are vacancy protection, easier to manage, and commercial loans options.

We're having trouble with using realistic numbers on our vacancy %, repair %, capex %, and management %.

It is probably rated as a C class neighborhood, but you said you're looking for cash flow, so obviously we will have a tough time finding cash flow in A or even B neighborhoods.Here's my monthly costs, not including vacancies and repairs:$586 mortgage & interest$166 taxes$34 water$46 insurance--------------------------------$832 total bills per month$1,650 total rental income per month*$818 total gross cash flow per month (before any possible vacancies and/or repairs)Purchase price of $98,000 (which looking back, I could have got for less but this was my first property and wasn't quite as good at negotiating). 

Also, I am in the Coast Guard reserves and am connected to the local military network so I can help him fill vacancies.

The idea is to always leave at least 20% of the equity in the home and make sure the house price wont be hit too hard (look at historic pricing) compared to the price you buy the house at and look at historic rents and vacancy of the area to determine even in bad times if you'll be able to rent it out for what your mortgage on it is at least (this is going to be our strategy).