I am aware that there is an opportunity cost that I could miss out on if I were to use my excess funds to pay off the mortgages in terms of using those funds to buy other rentals, but at this stage, my portfolio (8 rentals in total) is enough for me to handle.Thanks  

Again, back to the LTV, only the amounts paid in excess of fair market rents will be credited.

If you don't produce in excess of X% you don't get paid anything.

I have intended to put the cash flow excess back into the line so that I can speed up the pay off process.

The Heirs can then claim the excess funds (the amount that was paid above the taxes owed).    

it was to build up my cash reserves and look for invvestmetn opportunities;  also use teh excess flow from my other properties to pay down the mortgage on my 2nd rental; witht he goal of getting it paid off by the time i retire in 2015.    

Those that brought few years back can refi and pull cash out and buy again, and use the excess cash flow they have to feed the new acquisition.

Living in NYC, everyone is always telling me how crazy I am to not buy in NYC given the price appreciation that we've experienced over the last 10 year in particular - but I'm not sure that either market is immune to price depreciation even with foreign investors stepping in to sop up any excess inventory at ridiculous cap rates. 

Here a long term tenant is any tenancy in excess of 5-years and the landlord is required to provide three months notice.

This single family is on the multifamily property so the driveway is adequate but not excessive and although there is a large yard there isn't anything they can really do with that.