Financing will make a big difference when looking at cash flow numbers. If you put 20% down, or 25% down, which is what a lot of lenders will require for an investment property, then your cashflow is going to be better in terms of dollars, but lower in terms of a rate (%). I have a property I bought in Pensacola with my wife with a VA loan. We only ended up putting down a few thousand dollars and our cashflow is a little above $130/mo but our rate of return is almost 50%. It looks great on paper but with just one month of vacancy I lose a year of cashflow because we are so leveraged. I've found that you can always make the numbers change with financing, insurance, property management, etc. The trick is finding the sweet spot.
On the other hand I have a duplex in Chicago, we make almost $400 in cashflow according to the calculator, but we also put down 25% through conventional financing. So we make more in terms of dollars to cover any possible vacancies but our rate of return is on the lower end. We went to both extremes on our first properties it seems and it has taught us a lot.
Also, 9% seems a little low in this area for management but I still don't have as much experience with property management in this area yet. Is that what you were quoted? I've heard 10% is on the low end with some managers going up to 12% or even 15% and even one property manager I spoke with said that with multifamily they charge $100 minimum for each additional unit. So in this area 10% for a single family seems like a pretty good deal but once you look into multi-family the numbers don't look as good. For example, you have a 4-plex renting at lets say $2500, but a manager that charges $100 per unit will ask for $400, instead of $250 at 10%. There's always something to learn. There's always a price that makes sense for every property, and there's different ways to come to that price and the expenses therein. Real Estate investing is both exciting and frustrating because its so subjective.
I know I've rambled on a lot but I hope you got something out of it.