I've been using "Subject To" and other various creative techniques for thirty years and I've learned a few things along the way that may make it easier and less risky if you are trying to use them yourself.
1) First,...

The questions rellay is how much of these trades can he replace. 20% or 80%?

But the paper assumes the best possible outcome, what happens when it is not the best possible outcome (almost all the time it is not)? 

Amazing, wow, what an impressive outcome in such a short amount of time!

Depends on your market, but in general I would not trade market rent for vacancy unless I was in danger of losing the property or otherwise in financial distress and no vacancy was a necessity.

I have worked with a number of investors looking to trade up with a 1031 into a new build multifamily. 

completely gutted and redone What was the outcome?

The trade-off is that appreciation is more linear; it's not the same rocket ship upside Woodlawn has, but the cash flow stability tends to be better.How I’d personally evaluate it:If I want cash flow + stability, I’d lean Pilsen.If I want long-term appreciation + can stomach tax volatility, Woodlawn.Run both pro formas with the future tax number, not what's listed.

The best outcomes I have seen, are when the buyers reach out to the property manager during the option period.

The ability to move fast and lock in the opportunity is what made this deal profitable.What was the outcome?