Jason, it's a great question and one that my coach strongly advocates. Since he's several million ahead of me, I'm taking his advice seriously. So far I have spent about 8 months conducting due diligence on it. You are right that the concept has its detractors.
As a life-long advocate of pure life insurance, I found it amazing that permanent life insurance could actually have a valid purpose. This looks like it is it. It is called by several names, including Infinite Banking, Private Vault, Bank on Yourself.
Basically it is a life insurance product that has a relatively low death benefit and a high level of cash value. Maintaining a constant corridor between the death benefit and cash value prevents the product from becoming an Modified Endowment Contract which loses its tax advantage.
You can get some information online and in books about the concept. R Nelson Nash wrote what experts consider to be the primer, "Becoming Your Own Banker" which is 4.5 stars on Amazon. One reason it's controversial is that it is a practical implementation of Austrian Economics which is diametrically opposed to the Keynesian Economics taught in most western universities.
The use for it in REI is that you can use it for borrowing from when you have a short or medium term investment. You can borrow against it with guaranteed loans and low interest rate and the money is still represented in the policy as growing full strength. It's kind of like being two places at once. When you are in between investments, your funds are in a vehicle that is growing, not sitting dead in a bank or money market.
More benefits are that the funds are not part of the fractional reserve banking system (leveraged 10:1) subject to a bank run nor is it a part of the private retirement account system that the feds have their eye on as the only publicly available source of funds to keep the US debt afloat.
I have found two basis schools within the infinite banking world which I have yet to get to the bottom of. One school uses Whole Life product and the other uses an Indexed Universal Life product. The illustrations I have studied lead me to believe that the WL version is a predictable steady 5%-ish range and the IUL claims 8%-ish based on upside tied to the stock market. I am searching for a historical performance chart for a policy older than 10 yrs that exposes the fees to the insurance company. It makes me uneasy to put six figures of savings into the policy without having a good picture of what the fees will be twenty years later.
I would probably network with the members you heard about this from at your REIA. If they are actually using it, they may be the more advanced investors.