I also do not have any other investment opportunities on my immediate horizon, and it's passive money... 

Also, Interest rates are still at historic lows and although these low rates are likely causing inflated pricing in hard assets, a long term horizon should shelter you from any corrections.Consider a 2 or 3 unit property for a higher cash on cash potential.

I'm looking to expand my horizon and learn as much as possible and hopefully become a full time investor. 

I am just trying to do something new and expand my horizons! 

You really need to decide what Cap Rate/IRR is acceptable to you over your investment horizon, and go from there.

In short, it has expanded my horizons and allowed me to gain insights into areas and property types that I would have never dealt with in absence of my broker's license.If your trajectory is like mine, and your primary goal is to be an investor(and you have the income and/or capital to support your initial foray into investing,) then I'd suggest honing your investment skills first, and getting your license second.

For deals like these do you just take an interest only refi, for the partner takeout, to lengthen the time horizon with a longer call?

This was pre-Beltline, pre-PCM, pre-H4WP, etc... but all of those projects were either in the infancy of their planning phases or at least rumored to be on the horizon.

If I do not, I invest it in the stock market. 6 months or less is sort of my time horizon where I do not want to let the value of that cash drop in the market if I know I am going to need soon.

It also depends on where you are on your investing horizon.