Once you can make a sour and an Old Fashioned, the next jump in quality has almost nothing to do with your skill. A cocktail is mostly spirit, and no amount of careful shaking rescues a base that was built to disappear into a mixer.
So this kit keeps the same four categories and trades every one of them up — without reaching for a bigger brand. The rum is Jamaican overproof from a distillery with a cult following among bartenders. The whiskey is a rye finished in Grenache wine casks, a treatment that normally carries a heavy premium and doesn't here because the distillery is small and Californian. The tequila is artisanal Jalisco, made in a tiny operation that still uses traditional methods. The vodka is potato-based and made in small batches.
The test is simple: pour an inch of each, neat, before you mix anything. All four should be worth drinking that way. That is the whole standard.