Hold a note or take the money and run?

[John Alosio]

Hello BP fam
I come to you today with a problem; A GOOD problem, as they say.

The situation:

I've reached a point in my journey where it makes sense to sell one of my LTR properties. The fruit is ripe for picking. My goal is to grow my pockets in order to fund flips.

HELOC doesn't make sense because I already have a HELOC on a different property. i was recently turned down by a HML because my HELOC was not liquid enough for their comfort..

My dilemma:

I have a buyer lined up to purchase with a conventional mortgage, OR they could easily assume my current mortgage (lender approved).

If I go with an Assumption, I would get a small down payment, maybe walk away with 5k in my pocket after the tax-man is done with me. This would give me Truly Passive Income from a note that I would hold in 2nd position on the property. $600 a month in Pure Cash Flow! No clogged toilets or leaky roofs, every investor's dream, right?! BUT... this would not help with my liquidity issue. 

I'm in the building stage of my REI career. It seems wasteful to hold a note in my current position, yet I have this nagging feeling that I shouldn't pass it up.

What would you do in my position?

Thanks for taking the time to read, i look forward to hearing everyone's opinion.

cheers