I am in the process of researching my options when it comes to purchasing rental homes. I have money in the bank, but want to do this with as little money out of pocket as possible. 10% down would be the most I’d want to put down on a rental investment. My credit score is in the low 700′s.
I’d like to build a portfolio by working with the same people – realtor, lender, etc. My goal is to purchase at least one rental a year for the next 10 years, although I know that once I get started, provided I can make each one cash flow, I’m going to get the bug and want to purchase more than one each year.

Who has done this before and worked with lenders that went above and beyond for them and made the process not only easy, but somewhat enjoyable? You can always learn from others experiences.
What are the downfalls to little down on investment homes? Is the difference in interest rate that you pay by only putting 5-10% down really a concern?