I'm one of the contractors that rolled out instant transactions at CBA.

The feature is absolutely hype, and a selling point, or was til the RBA required everyone else to follow suit.

But it doesn't change the fact that fundamental things that cannot be allowed to fail should not be built on twigs.

CBA worked with Wells-Fargo to build a blockchain ledger, running atop skuchain, which itself Go and JS. That's a lot of hype and new in one place.

But it wasn't in a simple systems-critical place, it was done for one contract, with one customer first, with regulatory approval for the experiment, to see if blockchain technology was feasible. It was also not proof that this can scale, that needs more experimentation.

Lots of simple things are fundamental, and you do not mess with those.

Simple/complex isn't enough to say whether you should experiment, because experiments should be as far from impacting your bottomline as possible.

R&D should stay in R&D, until it is proven stable. You can't afford to build a house of cards.