There are some upgrades which are pretty incremental - going between Shimano's Ultegra and Dura-Ace is a prime example. Other upgrades are much more signficiant, like full topographic mapping on a bike computer rather than a breadcrumb trail, or switching to a set of deep section wheels.
I'd suggest another example for that list: the transition from a single BOA dial to two. Being able to adjust the retention tension across both the top of your foot is, quite simply, game changing.
