That way you can pay off quickly and still have the flexibility of a lower payment in the event that your plans change or you come upon harder times when the cash flow would be helpful. 

They are a private money lender that i'm considering moving forward with and has very flexible terms.

This is also where relationships help if you have a lender that you have been working with and he understands your overall financial position, he can be a bit more flexible; as @Jeff Dulla mentioned, I would wait until you are closer to actually making offers to get a pre-authorization.  

I have some flexibility throughout the day with my current job, so it allows me to work some of this as well during normal hours, but I usually focus the rest of my time right after I clock out.

Flexible appointment times. 

I am having so much fun thinking about the investment potential in RE and the possibilities for creating a life of increased wealth, time, and flexibility.

If your happy renting then rent away, it gives you flexibility.

In 5 years although I won't be what I call "financially free" I will be what I call "financially flexible" and that's good enough for me. 

I prefer to start with single family home but will be flexible to other type of properties.

I like the flexibility of being able to take out 401k loans, are there any products that will allow me to take loans out there?