If someone tells you that something you cannot make any sense out of (especially if you can't make sense out of because it is "proprietary) is (a) low-risk (b) predictable and (c) bears a well-defined relationship to something you _do_ understand, you should Stay Away.
If, on top of it, a bank says they can charge pretty amazing fees (because it's Versatile! We can make it do Anything! For a price) without getting into scarily risky territory, regulators really ought to be hearing warning bells. We've been through variations on these theme several times now, and it just seems to always turn out to be a leverage, lying, or, usually, both. Which is boring, and not any of the things that we were told it was.
If, on top of it, a bank says they can charge pretty amazing fees (because it's Versatile! We can make it do Anything! For a price) without getting into scarily risky territory, regulators really ought to be hearing warning bells. We've been through variations on these theme several times now, and it just seems to always turn out to be a leverage, lying, or, usually, both. Which is boring, and not any of the things that we were told it was.