Any advice on if we should use it to pay off our loans against two of our retirement accounts (that we took out for the downpayment on the first STR) in order to lower the monthly bills or if we can/should cash out one or two of our retirement accounts (457 and/or 403b) and pay off the loans? 

And I have a good cash flow to do this.   

They tend to appreciate a bit less but cash flow well.

We were scheduled to NET over $7k in cash flow in March...

HML puts buyer into title .. buyer house gets rehabbed... 442 refi and HML cashed out and owner has their rental. prior to 08 though you would normally get 5 to 8k cash back instead of putting money in.

Now I have $550k cash left over to either buy another properrty or invest it another way.

These homes are cash only deals though.

I'm a first-time investor interested in seeking cash flow and appreciation through rental properties.

Unless you plan to sell your home soon, cash out refi it.  

Purchase price: $600,000 Cash invested: $120,000 Contributors: Michael Ablan 10-unit, multi-family property in an area I already invest. 8 of 10 units have been interior rehabbed.