Please allow me to weigh in on this: You don't take % ROI to the bank, you take cash.. So, it all depends on your situation and your goals. I'm an investor in my mid-50's who is looking to retire at 59. Therefore, I built a portfolio of high quality rental properties using 25% down so that I was always cash flow positive - which is very important if a market downturn should happen. Once I got to the desired # of rentals (that would produce the desired amount of cash flow should I not have any debt) then I stopped buying additional properties and started taking all that positive cash flow and paying down the mortgages in a systematic and targeted fashion. So, you may look at my ROI and say I'm making less than I could had I just taken that cash and continued to buy more houses, but in reality, I'm making a lot more CASH - which is what I can take to the bank and also what I will use in retirement. I don't pay bills with ROI!!! Please allow me to reiterate: It all depends on your situation and your goals!!!