The assets of SDIRA A now include Owner B's IOU in favor of SDIRA A, and the assets of SDIRA B now include Owner A's IOU in favor of SDIRA B. 

Nearly every deal is a multi-offer scenario, so the market is really in favor of the seller since they can easily turn to the next guy and sell their home for full price.Currently we're experiencing a mass exodus from the Bay Area, and tens of thousands of people are leaving for surrounding counties because housing is so much cheaper.

I looked into them on this forum and they seem much move favorable (higher returns in the low teens, relatively hands off even if they turn NPN).

The LLC seems to be the most-favored form of ownership (certainly the most-discussed in REI circles).  

These days I am favoring an investment strategy that allows me to buy into a portfolio of 10 SFR at a time, and co-own with the managers.  

Be sure to talk to a good accountant before any possible sale in order to make it as tax favorable as possible. 

Should I do both evaluations, and then choose the "best" one (in my favor) when making my offer?

One very passive investment strategy I favor these days and that is producing very nice returns involves investing in portfolios of 10 SFR at a time, co-owned with the managers.  

Later, as you get more experienced, you can return the favor and have folks help you.  

They are taxed separately, so I should be able to buy them as two quads (with favorable financing).