A few additional things to consider between the two loan types: prepayment penalties, probability of closing, points/ fees.... and vesting (LLC or personal). 

What made you interested in investing in this type of deal?

There is no uniform way to structure these types of deals.  

I've been in Real Estate since '87 so I like to invest in what I know but outside of my company, in my personal portfolio I have about 20% outside of Real Estate assets in other types of debt instruments, private equity, and a bit in the traditional stock market. 

That also doesn't jive with the 650 flips over 10yrs.650 over a decade, 65 flips a year, that's a lot, bit it's doable. 20, 30 or 50 flips a month.....Lol, I'd be shocked if I saw anyone come close to that type of volume.

You should verify whether you can establish this type of LLC in Texas. 

If you are looking at more DSCR type options for a stabilized property, then you can layer in market or actual rent, taxes and insurance estimates to calculate DSCR rate.

Similarly depending on what type of property they bought, partly determines what type of tenant they attract. 

While a mini storage, apartment building or some other type may sound great they all come with their own issues and stresses. 

The goal with this type of investment is to have your tenants pay most of the ownership cost.