I can pay them off now but it makes sense to have the liquid to invest. 

It's always important to consider your exit strategy and it would be easy to liquidate this property later, should you need to.  

Perhaps liquidating was foolish given the trajectory in Avondale and Logan?

My situation is this:I have about $150k in assets broken down by $50k in cash, $20k in a 401k, $50k in Roth retirement accounts (can be pulled out without penalty but would prefer to avoid losing tax advantage), and $30k in liquid securities. 

This might be more of a polling question...if you had money in the stock market and 401K and savings etc... would you liquidate those sources to buy more real estate or do folks believe in the diversification of investments?  

Frequent inspections, perimeter spray all units, and treat each occurrence asap.

what is the premium for liquidity?)

Why does a liquidity event have to happen?

Just picking only multis doesn't always guarantee success, and for me  I'd MUCH rather prefer a balanced portfolio - Multis for high cashflow, singles for equity and liquidity. 

I can cover 20-30% downpayment but dont have enough liquidity to buy all cash.