Actually, if I want a bit of masochism, I just need to try to make an espresso with beans even just lighter than dark roast that doesn’t taste of battery acid! And boy have I tried enough packets of beans in trying, of all sorts of roast levels, to last a lifetime.
Seriously, if Lance is only to be half believed, the window for error of grind, brew pressure and temperature and not to mention tamping and puck prep, is way wider than E61 espresso. Even once, let alone for consistent shots.