I use all the rental cash flow to pay these loans off asap, then repeat.

Owning a duplex at 20 is a huge accomplishment, and it’s inspiring to see you’re already planning your next move.From my perspective, real estate investing is a long-term game focused on building equity, paying down debt, and maintaining stability over chasing short-term cash flow.

Regarding your other questions:  - If the going value is $260/SF, why would you pay more than that?  

Lots of folks invest here. 15+ years Realtor/Wholesaler experience.

They develop, they build, they finance, they property manage, they will have HAO, cleaning crew etc. etc. etc. so the subsidiary companies make money every step of the way.From investor perspective: The investor pay $15 K to reserve the right to purchase 25 multiplex over the year of next 5 years. 5 each year.

Or they have it figured out and are going to cure via paying or modification etc etc. 

We had success in summerlin with insurance company paying .. over a 24 month period we had 3 tenants   fair market rent at the time was about 2200 or so non furnished.. we got 4100.00I did not like the turnover so I put it up as furnished rental and got 3500 and its going into its second year with a superb tenant. so seems like a happy medium for us.. 

Any positive cash flow should go towards paying off debt.

Somebody somewhere had to pay for that real estate at some point and has continued to pay for it since.

If your brother is looking to invest in real estate largely from a tax reduction standpoint they should pay a qualified real estate tax strategist to review their specific situation and what may or may not work for them.