Few organizations have higher uptime requirements and so much money (literally) at stake... I'd imagine that it'd be tough to push through any kind of software/

Few organizations have higher uptime requirements and so much money (literally) at stake... I'd imagine that it'd be tough to push through any kind of software/system change, let alone large-scale ones. (If it ain't broke, don't fix it.) There's substantial risk to upgrades like that unless they're flawless.