I like paying that thing down.. but thats me and i know its not mathematically correct. 

I still don't see mathematically how it would make sense.  

Easy -- 16 is a pretty nice mathematical number. 

Mathematically, it seems equivalent to me either way.  

It is less a mathematical decision and more emotional for me.Interesting point you bring up about appreciation versus return.

Some people prefer to have their primary always paid because it lets them sleep better at night; some people want that liability to become an asset... that goes deeper into your personal preferences and is something you would have to answer on your own, mathematics aside.Best of luck!

I graduated from the University of Houston with a degree in mathematics (mostly out of love for the subject) not really knowing what I wanted in life.

Mathematical fact.  

Are you adding the leasing fee in under miscellaneous expenses for the year or would you up the PM % to mathematically cover the possible leasing fee each year (or two years).Example: SFH rents for $700/month.

Now, there's no question that, from a mathematical standpoint, the less you spend on a property that cash flows the better your return on investment is.