to redeem the units on demand.

You've still not quite grokked it.....these Units have no "demand" built in, as futures contracts have.

They may be presented for redemption against supply or consumption, that's all, but that's still pretty powerful.

What Units do is decouple speculation from the physical market.

It means that if you can't consume now, you would require a discount against when you CAN consume. It's a forward purchase - a hedge, but 100% margined.

"The future is already here -- it's just not very evenly distributed" William Gibson